In the present case, either the UB in the code is by mistake or lack of awareness, and then it's warranted to point out the error, or, as GGGP argued, the author deliberately decided to neglect safety or correctness, and then in my opinion you can't reject the criticism as unwarranted if the project's presentation isn't explicit about that.

I'm not making anything the author's problem here. Rather, I'm defending my criticism of the code, and am giving arguments as to why it would be good form to make it explicit if a project doesn't care about the code being safe and correct.

Misery loves company, and losers love dragging other people down to their level so they feel a little less lonely.