It can be stretched to read that way, but I believe the context makes it clear that he is primarily speaking about those he observed and spoke to in that factory.
For example, the last sentence phrase "I told this to the French union workers to their faces" is clearly referring to specific workers at a specific site, not all French workers (or even French union workers) everywhere.
He does emphasize the descriptor 'French', but that seems both to rub a little salt in the wound of the national official he's responding to, and perhaps to contrast those he's describing with non-French workers at the same factory, or with workers in similar tire factories outside France. It isn't evidence the author has the same judgement of all French workers, even though that expansive interpretation is an easier strawman to knock down.
