Having dug in on this a little more, it seems clear that the op-ed wasn’t supposed to send any signal about 2020, especially not about Romney’s intentions. One objective was to put down a marker so Romney won’t necessarily have to respond to every Trump tweet, which actually creates the predicate for him being more like other Senate Republicans who tend to duck and cover in the hallways rather than being something completely different. But Romney does feel very strongly about the character critique of Trump, which is one reason he was willing to let it rip, without over-thinking about how the op-ed would land.