Really? Never noticed anyone with a beard having an issue with HAHO jumps. Getting to the ramp edge with all the equipment can be a massive challenge, but the beard is trivial. Quite a few that operate the front end have been known to wear a beard and cope with the pre-breathing and beyond just fine.
Beards and AEA is not new, novel or a contentious safety point. It may be new to some in the RAF but that alone does not make it a safety issue. This reminds me of PCS giving us a short jacket rather than a shirt, before making some of us tuck it into our trousers 'like we used to'. Change is just too much for some air officers.