Oh how cute. Little nosewiper has finally stepped onto the 60-90 diamond, and he’s got himself a catching personal instructor / coach who’s taught him this crap, or he’s imitating the Big League catchers, thinking that because he’s now a tough teenager, he can get the adults riled up by being demonstrative.
Yes, I have witnessed travel-ball parents (I call them “travel-ball invested parents”… either “travesties” or “Foul TIPs”… I’m mulling it over) try to impress upon the umpires – thru the fence – that they have video; or, barring that, they go track down the TD or Site-UIC, phone clutched in their hand, to show “just how bad (that) Blue is!” This is typical USSSA modus operandi, but not limited to just USSSA. Of course, since USSSA (prides itself!) on using OBR (predominantly), you get all manner of grief at amateur umpires expected to not only call rules-&-zones-meant-for-pro-adults-but-used-by-kids, but to treat those same kids on an ever-shifting scale ("too harsh, Blue! No feel!" – "that's a little kid zone you're calling, Blue! My players are savages!")
While I agree you shouldn’t ignore it, I’d spar with it, implying that it is not effective, not applicable, not worth it, and should not continue. I’d rather channel the kid towards the futility of continuing or pursuing it, rather than going right to showing / detailing the nuclear option. I’d rather spar with the kid, saying things like “What’s that (gesturing) for?” or “You know that’s not going to work, right?” and have him tell his coach, “Blue’s on to us (or something to that effect)”, instead of, “Blue’s said he’s gonna eject me if I do ~this~ again”… because at whatever age < 18, it’ll always come off as I’m the big, bad Blue who doesn’t have a feel for the kids "just being kids".