It can be a tricky issue.

In the above example, logic definitely = workers. "employers" is another possible noun, though, so we don't want something that appears to point to employers structurally but workers logically. So, yes, you understand.

Note that the structural setup is NOT always required; it just adds a certain expectation. But if you know that the subject could not possibly be the antecedent - because there's a mismatch in gender or number, for example - then it's okay not to have a match between the case of the pronoun and the noun that is its antecedent. (See below.)

Because she wanted a good grade, the girl studied hard. "she" = subject of subord. clause; "the girl" = subj. of main clause (Can also swap "she" and "the girl": Because the girl wanted a good grade, she...)
Because she wanted a good grade, the girl asked the teacher for extra help. No ambiguity. "she" = subj. of sub. clause; "the girl" = subj of main clause (again, can swap "she" and "the girl")
Because she wanted a good grade, the teacher gave the girl extra help. Wait. Who wants the good grade? Note that "teacher" is a possible antecedent for "she" AND teacher is in the expected structural position to match with "she." Those two things together create the ambiguity.

Because she wanted the cat, she bought it. Because she wanted it, she bought the cat. Fine again - this is an example using objects (it and the cat).

Note:
Because it was cute, the girl bought the cat. This one's okay, too! "it" is in the subject case, but "it" cannot refer to a girl. "It" is not a possible or acceptable pronoun to refer to a person. So we know that the "it" must be talking about something else, and the only other noun is the cat.