To be perfectly clear, my frustration is really with the Chinese guys my son is sharing Halls of Residence with.
My son had a tough time and was flooded out during the storms earlier this year and the university were kind enough to take all those students into halls again. He has a lot of work to catch up on because of this and also has on-line exams looming. They've had "parties" in their kitchen with other Chinese people and they always leave the place a mess (which, I suppose, is normal for students) but...at this point in time... it is completely unacceptable to disobey the rules/law about isolation.
Summer is approaching and most universities shut down a lot of their facilities over the summer when students return home. My son is going to be in a difficult position of either not being able to return home or put the rest of the family at risk of infection.
Summer is a ways off yet. There's a lot that might still come out in the wash before then to ease some of your concerns. Antigen testing is rapidly expanding and I'd be pretty confident that by June time you'll be able to request your son be tested before he comes home which whilst not perfect will provide a high degree of confidence that he's safe to come back if the test is done after seven days of him self isolating and that he doesn't use public transport to return home. Treatments are improving and the modified CPAPs appear to be making a significant difference to survival and speed of recovery. Plus it shouldn't be too much longer before they crack the antibody test which should make a vast difference in understanding relative risk.
What may be more of an issue is that once home he'll need to sacrifice contact with the outside world pretty much to the same extent as you to be sure that you remain shielded.