Since Christmas Eve, the tweets of George Ciccariello-Maher, associate professor of politics and global studies at Drexel University, have been subjected to scrutiny and criticism.

On Dec. 24, his tweet saying "All I want for Christmas is white genocide" went viral, with many of those forwarding it saying that Drexel should fire him. Drexel condemned the tweet but didn't fire Ciccariello-Maher. Now, however, after the professor's tweets and comments about the mass shooting in Las Vegas, the university has placed him on administrative leave. The university says the issue is safety, but not everyone is buying that explanation.

Drexel's statement is as follows: "The safety of Drexel’s students, faculty, professional staff and police officers are of paramount concern to Drexel. Due to a growing number of threats directed at Professor George Ciccariello-Maher, and increased concerns about both his safety and the safety of Drexel’s community, after careful consideration the university has decided to place Professor Ciccariello-Maher on administrative leave. We believe this is a necessary step to ensure the safety of our campus."

Ciccariello-Maher posted a series of tweets after last week's Las Vegas mass shooting in which he noted that the shooter was a wealthy white man and said that he didn't think gun control, as advocated by liberals, would prevent such shootings. "To believe that someone who would shoot down 50 people wouldn't circumvent any gun law you pass is the height of delusion," he wrote.

But the attacks on the professor have focused on what he said was the cause of the tragedy in Las Vegas. Ciccariello-Maher made a series of tweets in which he blamed "Trumpism" and the entitlement of white men. "White people and men are told that they are entitled to everything. This is what happens when they don't get what they want." he wrote. And "the narrative of white victimization has been gradually built over the past 40 years."

As has happened periodically in the last year, the tweets were mocked and attacked on conservative websites, and then the professor and the university started to receive email messages (many vulgar and some threatening), along with calls for his dismissal.

Ciccariello-Maher has said that his ideas are regularly distorted by his critics -- and that the Las Vegas killings show that the real killers in the United States are not those imagined by President Trump and others. In fact, he has said repeatedly that the reference to "white genocide" in his pre-Christmas tweet was understood by his academic colleagues as a joke, because he has said repeatedly that white genocide does not exist. In this column in The Washington Post, he elaborated on his tweets about Las Vegas and also noted that he is one of many scholars on the left who write about race whose dismissals are demanded by many on the right. His headline on the piece: "Conservatives Are the Real Campus Thought Police Squashing Academic Freedom."

In April, Ciccariello-Maher was again in the news when he tweeted about his reaction when he saw a passenger in first class give up his seat on a flight. "Some guy in first class gave up his seat for a uniformed soldier. People are thanking him. I'm trying not to vomit or yell about Mosul." The reference to Mosul was to a March air strike by U.S. forces that The Washington Post reported "could potentially rank [as] one of the most devastating attacks on civilians by American forces in more than two decades."

In subsequent comments, Ciccariello-Maher said he wasn't trying to attack that particular solider, but to question the way many Americans make symbolic gestures of support for the military without examining military actions or demanding that the United States provide sufficient health care and support for other needs of veterans and active-duty military.

Throughout the various controversies, Drexel has criticized his statements and also said that the university was losing some prospective students and donors because of the furor over the tweets.

Over the months, many advocates for academic freedom have, while stressing that they didn't necessarily share Ciccariello-Maher's views or his use of rhetoric, said that the university should be standing up for his academic freedom with strong statements of support for his right of free expression.

Dakota Peterson, one of Ciccariello-Maher's students, said in an interview that he did not believe Drexel was being truthful about the safety issue. If that was the concern, Peterson said, why hasn't the university reached out to him and other students to check on their safety?

"We have a right to our professor in our class," he said. Peterson is currently taking a course on race and politics from Ciccariello-Maher.

As for Ciccariello-Maher, he is also questioning Drexel's action, even if there are real threats.

"Drexel has put me on administrative leave, citing threats of violence, but I am optimistic that this decision -- harmful to myself and to my students -- will be reversed," he said via email. "Obviously, allowing the mere existence of threats [to] dictate the limits of academic freedom is not acceptable."