not so pushut, joseph.
i remember seeing a rav moshe somewhere on this. he was asked if it’s muttar to teach children in a conservative shul and he answered that it’s not assur, but if there’s another choice it’s better not because of “kedoshim tihyu.” he wouldn’t answer the question, though – he sent them to Philadelphia to ask the rabbonim there. (i think there was a second question too, like if the building had a separate entrance or something. can’t remember – look it up.)