Nomesorah, as a talmid of one of the biggest talmidim of rav aharon (who only having been there for a year was approached to write mishnas rav aharon; he declined and went to rav berel subsequently at the encouragement of a friend who also became a major rosh Yeshiva), i am sorry but this is simply mistaken. It’s as demonstrably false as the people who go around saying that the satmar rov wasn’t *really* anti zionist. Talmidim of the talmidim are all still around, go and speak with them instead of getting information online or from people who left the yeshivos. My rosh yeshiva never referred to rabbi yoshe ber as the bostoner rov, i believe you are conflating that term with what the brisker family of rabbonim refer to him as – “the bostoner soloveitchik”. If anyone was a “bostoner rov” among briskers it would have been rav Mordechai savitsky, who was a major posek and lamdan who was rov of the yeshivishe sector in boston.
There’s a big difference.