“Nor did it seem to have been of concern to Hazal in their allowing Michal to wear tefillin. “
The Gemara in Eiruvin says that Michal wore Tefillin, but the Rabbis did not object. Clearly the implication is that there is usually something objectionable about that (be it guf naki or whatever). To make it sound like it’s a free for all is incorrect.