Do you know what a metaphor is?

No GCC --hlep isn't in the c standard.

But it is a simple example to illustrate how programs react when it receives something that isn't in the spec. GCC could do anything with Gcc --hlep just like it could do anything with INT_MAX + 1. That doesnt mean that all options open to it are reasonable.

If I typed in GCC --hlep I would be reasonably pissed that it deleted my hard drive. You pointing out that GCC never made any claims about what would happen if I did that doesn't make it ok.

If you come across UD, there's reasonable and unreasonable ways to deal with that. Reformatting your hard drive which is presumably allowed by the C standard isn't reasonable. I would contend that removing checks is also unreasonable.