I agree that the phrase "greedy Frenchmen" can only be reasonably interpreted as the speaker believing it is typical for Frenchmen to be greedy.
But contrast another phrase of the same pattern, say, "fundamentalist Christians". I don't think anyone reasonable would interpret this as saying "fundamentalists, as is typical for Christians" (it could depend on the speaker though). Instead, this phrase would be broadly recognized as selecting the fundamentalist subset of the set of Christians (most of whom are understood not to be fundamentalists).
The difference between these two phrases is that in the first case, the two properties being discussed (being greedy and being French) don't really inform one another. There is no broadly understood "typically French way" of being greedy (afaik). So by putting these two properties in proximity, the speaker tries to construct the association. In the second case, the properties (being fundamentalist and being Christian) do inform one another. If you'd get both pieces of data separately, the meaning is different: a person might be Christian and fundamentalist about something other than Christianity. So the phrase "he is a Christian fundamentalist" is more informative than just getting these two pieces of information apart, since Christian fundamentalism is a somewhat specific set of beliefs.
So you only argue why it is linguistically possible for phrases of the pattern " " to be interpreted as "s are typically ", but you don't argue for why this must be the case for "toxic masculinity".
And it seems quite clear to me that the phrase "toxic masculinity" is in this regard a lot closer to "fundamentalist Christians" than to "greedy Frenchmen". There is a qualitative difference between being told "his displays toxically masculine behavior" and the two separate pieces of information "he is masculine" and "he is toxic"; this is because there are many ways to be toxic, and the phrase "toxic masculinity" asserts that there is a certain type of toxicity that arises from trying to be perceived as very masculine.