Oh COME ON. 5.3 isn't even officially supported. Move to 5.6. Use the market power to set a bar vs crawling over one years after the race is over. Admittedly, this is something for WP itself to do more than Buddypress, but this is getting a bit silly.

As for the pre 5.6 people... they can upgrade. Or more precisely, their hosts can (and will if WP lays out a timeline for a move to 5.6). When I read “For many (most?) people running BuddyPress, updating PHP is emphatically not a simple task,” Gorges said." it makes me wonder - do most people even do their own updates? I'd bet not, that they use hosts who manage that behind the scenes... so it's irrelevant whether the BP user themselves is comfortable upgrading PHP.