After 9/11 and even before the shoe bomber, someone predicted that the only truly safe flight is one with the passengers naked and handcuffed to their seats. It hasn’t come to that, so probably won’t at the movies, but neither is TSA operation any better than “security theater”, rather than true security. The same will doubtless be true of whatever security measures are adopted for movies.
But after all, Mr Holmes didn’t buy a ticket anyway, did he? Maybe the solution is to booby-trap emergency exits. Or no, that wouldn’t work . . .