The law is the law, that is the problem. He owned weapons illegal by English law, that cant be avoided. Like you, I have no problem with him owning them, but the law is what it is today. His age, at least as the offence and charging of the offence, is irrelevant.
As an old man, he will get a fine, a slap on the wrist and the weapons taken off him.
Hopefully, whatever assailants he encounters in the future will only rough him up a bit, and only steal meaningless "stuff" that's not worth making a fuss over, like his dignity and peace of mind.
I don't recognize "laws" that violate one's natural rights.