I have no idea or practical experience with anything this low-level, so idk how much following matters, it's just someone from the crowd offering unvarnished impressions:

It's easy to believe you're replying to something that has an element of hyperbole.

It's hard to believe "just do 2x as many instructions" and "ehhh who cares [i.e. your typical C program doesn't check for overflow]", coupled to a seemingly self-conscious repetition of a quip from the television series Chernobyl that is meant to reference sticking your head in the sand, retire the issue from discussion.

There was no hyperbole in what I have said.

The sequence of instructions given above is incorrect, it does not detect integer overflow (i.e. signed integer overflow). It detects carry, which is something else.

The correct sequence, which can be found in the official RISC-V documentation, requires more instructions.

Not checking for overflow in C programs is a serious mistake. All decent C compilers have compilation options for enabling checking for overflow. Such options should always be used, with the exception of the functions that have been analyzed carefully by the programmer and the conclusion has been that integer overflow cannot happen.

For example with operations involving counters or indices, overflow cannot normally happen, so in such places overflow checking may be disabled.