What you put as an example isn't a footgun if you know how the language evaluation rules work. Once you understand that the "footgun" explains a dozen behaviors, which may be a weird behavior but it is consistent.
This is so much so that it is described in the Zen of Python: There's preferably One Way to do things, but that one way may not be obvious.
A gun becomes a footgun when you put it in the hands of someone who doesn’t understand how it works and they promptly blow off their foot.