to joseph—I’ll refrain from commenting on this becuase i don’t have R’Joshe be’er direct words. You quted one talmid, yet there are others who do differently, so, unless one has direct written sources, I’ll refrain from drawing any conclusions on that.
to “mybat”: if you look through the mishneh berurah (fom se’if 5 onwards) and other “nos’ei keilim’, you will see that there is a number of different minhagim, so there is no obvious rule for all. Thye ALL agree,however, that this is ONLY a minhag and it is not the actual “halocho”. (see mishneh berurah se’if 6, be’er heitav also).
The conclusion of all this is simple: halachacally, “divrei torah einom mekablim tumeh” , the words of torah are not subject to any tum’oh and hence, women, even niddos, can touch and read from the torah (joreh deah 282) and it only became a minhag in various european places to put certain restrictions on what a woman can do during her time as a “niddah”.
minhagim clearly have their place and are important but halachacally, there is no issur in entering a shul ,davening, touching a sefer torah ,etc.for a woman anytime.