Actually, what's at play here is not the implicit domain restriction of natural language quantifiers, because he obviously didn't restrict the domain of the quantifier to just those mathematicians that have an Eastern European last name; that'd make the statement trivial. Rather, the phenomenon we see here is what's self-explanatorily called "loose talk", where you can say things that are strictly true when they are close enough to being true, i.e. when the exceptions don't matter for current purposes.
A typical failure mode for computer scientists, who typically are trained to check statements against boundary cases / extreme values, to make sure an exception isn't thrown / that the result isn't out of bounds.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.