Or extension of the POSIX terminal control flags could result in gaining a mode, which the curls and tars of this world would use, to express to a terminal "ignore any terminal control code I write out; I don't actually mean it".

But this would require coordination in POSIX, in the terminals, and in programs using the terminal :-/

But the advantage would be that then you'd be able to put your terminal into this safe mode by default. And the terminal can alert you when a program is writing out control codes that are being ignored, and then you can whitelist them and/or get those programs fixed to fence off their sections of "I'm going to output data from god-knows-where now" with this new terminal mode.

It's not going to happen but we can dream ;-)