^^^^^^ a bit of an eye-opener for me, too, I can only assume that the old Regs were being so regularly & blatantly abused that WR (World Rugby) saw this as the only remedy. You'd like to think the chances of two LH- or TH props from the same team both failing HIA's is remote enough that the scenario you've outlined doesn't occur, but who knows, one day it might happen & they'll have to revisit it.
BTW I was watching Grassroots Rugby (now sponsored by "Haati" (who I've never heard of & nor apparently has Google) & officially a Maori TV production) & to my horror Athletic were 0-2 for the season! It's gotta be a Wanderers/ Old Boys conspiracy! On a brighter note the H-K match they showed had Rahui in it so at least they're still going, I seem to recall they were a bit touch & go a while back.