It's fine to celebrate in front of opposition players* but the reason barely anyone does it is because there is always a massive risk of insta-karma.
* The idea that instantly celebrating as he scored was some sort of celebration to the Villa fans is hilarious, literally no player ever does that -- he was clearly goading Varane and Onana. To the point where Varane (normally a pretty cool and unaffected guy) had to be stopped by the ref for complaining and going after Luiz. But as I say above, it's fine. If you dish it out you always run the risk of getting it back. And he did.