Fun fact: That's not how Twitter works, that's how media monitoring software who scrapes the entirety of Twitter or any other media channels for anyone remotely mentioning their name works. Hey look, a nice compiled list of anything that mentions my name, let me go down the list and broadcast any slights, perceived or otherwise, to the world so that the most rabid and unreasonable of my fanbase can jump down their throats.
Dying at you people who think Gervais is sitting there doing some innocent Twitter search.
A celebrity who uses this and responds is either a drooling fucking idiot or knows exactly that engaging an average person will draw the attention of all his followers to said average person, thereby invoking the same weaponized fuckery that makes the internet such a great place. Except it's over, you know, some blase internet sarcasm as opposed to being anything actually damaging or offensive.
A stupid fucking celebrity is being a massive shitbag at scale, and some of you can't tell or don't care that interpersonal dynamic doesn't work the same way when one side of the conversation has a massively disproportionate share of voice and power. Thankfully this particular instance is at least relatively benign thus far.
Remember how money and resources TOTALLY don't have any influence when it comes to speech? Yeah.