It is difficult to place confucianism in either Virtue Ethics or Deontology, since in his teaching there is a high emphasis on both( Analects 5.7 & 14.17 ). Although trough my study and understanding of The Analects I believe that the answer is Virtue Ethics. Also the question you have asked , does suit Zilu specifically well :

Analects 15.4.

The Master said, "You [Zilu], there are only a few who understand virtue [de]."

This tells us that Zilu is someone who has the capability to understand virtue since a few pages after this we read :

Analects 15.8.

The Master said, “Not to speak to a man who is capable of absorbing what you say is to let the man go to waste. To speak to a man who is incapable of absorbing what you say is to let your words go to waste...”

Confucious' views on this topic are not always clear but in his comments and defense of Guan Zhong whose actions were not align with what was considered his duty are strong argueements that Confucious leans Virtue Ethics :

Analects 14.17

Zigong said, “Guan Zhong was not humane. When Duke Huan had Prince Jiu killed, he chose not to die, and instead he decided to serve Duke Huan as his counselor.” The Master said, “When Guan Zhong served as the counselor of Duke Huan, he saw to it that Duke Huan would stand as the lord protector among the regional rulers, drawing all the states together under one empire. To this day, people [of all the Chinese states] still benefit from what he accomplished. If not for Guan Zhong, we would be [like the barbarian tribes,] wearing our hair

And in Analects 5.7 we can find insights into Confucious' and Zilu's stance on whether duty trumps the moral way :

The Master said, “If I cannot practice a proper way here in this world, then I shall take to the open sea and drift around on a bamboo raft. The person who will follow me would be You [Zilu].” Zilu was overjoyed when he heard these words..."

Here in 5.7 I argue that we have a denunciation of deontoligy without the moral way. Since if Confucious found that he could not practice the moral way in this world that he would turn away from the world and his duties and sail the sea. Also worth noting is that out of all his disciples he picks Zilu to come with him on this rhetorical journey.

Zilu is one of the three standout early students (Yan Hui, Zigong, Yan Hui) who followed Confucious into his exile. On Yan Hui we have very little probably since he passed away early but he is mentioned in the Analects to Confucious' best student someone who's knowledge might even surpass Confucious( Look Analects 5.9 ), Zigong who has often protested when he did not agree with Confucious( As in 14.7 ), but Zilu is mentioned as a very faitful student who tried to apply Confucious' teaching as mentioned in 5.14

Before Zilu was able to put into practice what he had heard, he only feared that he might hear something else.

Based on this I believe that Zilu's philosophy is reflective of Confucious'. Since we can say that Confucious' philosophy is definitively leaning to Virtue Ethics, we can assume the same for Zilu's.

At the same time we can not deny the presence of deontology :

Analects 4.1.

The gentleman is conscious of [not breaking] the law, while the common man is conscious of what benefits he might reap [from the state].”

The idea that Zilu comes to realize in Analects 18.7 is a core belief in Confucious philosophy, that public service is a part of the moral way. The word Junzi can also be translated as a person of high standing, or ruler. But not everyone who is in public service is a moral person similar as in :

Analects 14.4

The Master said, “A person who has integrity is sure to have something to say, but a person who has something to say does not necessarily have integrity."

Further understanding of what a Junzi is, and how public service is a part of the moral way can be found in Analects 14.2 where Confucious is again talking to Zilu :

Zilu asked about the gentleman [junzi]. The Master said, “He cultivates himself in order to acquire a respectful attitude.” “Is that all?” “He cultivates himself in order to give ease to those around him.” “Is that all?” “He cultivates himself in order to give ease to the people. To cultivate oneself in order to give ease to the people—even the sage rulers Yao and Shun found it difficult to do.”

And the final sentence is something I have not yet understood myself but Zilu it is very much reflective of Confucious again, as in Analects 14.3 ( With Zilu again )

Zilu spent the night at the Stone Gate. The gatekeeper asked him, “Where did you come from?” Zilu said, “From the Kong family.” “Is that the person who knows that what he is working toward simply cannot be realized?”

The gatekeeper's comment is in refference to Confucious.