Oh. I get it now. I mean, sure, at least some of this is probably just the fact that Areru, sans many of Alchemists' originally highly introverted/socially awkward experiences just seems to be a more extroverted person when he feels like it.
Some is probably a latent desire for attention as a result of a lifetime of loneliness, albeit with the safeguard of an anonymous identity.
Most of all though, he's deflating the Masquerade. It's going to come down inevitably whether by the advancement of technology or the progression of anime plots...but there's still a lot of potential for chaos and bad actors. If it gets deliberately popped though? Done so in an extremely hammy/disarming way to mitigate initial panic? And done with the kind of wide-spread proof that the Mages Association can't subtly or overtly quash? It's kinda funny how a whole Ward of people can know the Youma exist and yet there isn't a Masquerade breach, mass panic, or the rest of Japan in the know...sounds like local leaders are in on things or mind-controlled, and the masses have a basic-but-pervasive filter on their concern/perception - though that may be more the Youma or Sailors. Either way...collaborators, puppets, and a weak wide-area spell or ward? Don't do too well at dealing with a live broadcast to thousands or millions of people and the kind of video evidence that can't be faked (by tricks, or digital software that doesn't exist yet.)
I figure the real reason for the Adamant Knight, the one more important then inserting himself into the Sailors conflict even (at least, as far as explaining why it's the Adamant Knight intervening and not anything else)...is specifically breaking the Masquerade as early and gently as possible. Hams are harmless after-all, and while the Youma should be incredibly terrifying (and no doubt are to anyone read-in on them or experienced enough to get how powerful they are)... they're also stupid looking idiots regularly defeated by cute school girls. That's probably about as good an introduction as the public can get to how the Supernatural isn't all incredibly terrifying and they need to turn their brains off and flail wildly...but it still has more clear positive/relatable parts that make people inclined to actually THINK and empathize. While also not giving them (in this case, the power players and not the plebs) any particularly foolish ideas on how lucrative or useful this magic thing could be with some 'reasonable' leverage.