The issue is that it's a spectrum: how easily you can shoot yourself in the foot, especially on accident, without awareness of the risks. And perhaps what the consequences are when you do. Risk and consequence. C is high risk and also high consequence.

In higher level languages, you can't shoot yourself in the foot nearly as easily in such a way as to trivially create a correctness problem and security vulnerability (like a buffer under/overflow). Languages like Java and C# make it pretty difficult to shoot yourself in the foot this way (though you still can in other ways, like with incorrect concurrency). Rust makes it a lot harder to shoot yourself in the foot across the board, especially on accident (i.e., without being aware that you're something dangerous and low-level, viz. `unsafe`).

The "categorically" part is a useless qualification, you don't program in a binary world, the ease with which a footgun is possible in a language is very important and can't be reduced to isPossible