As has been said, if he doesn't want you to fix it there's little you can do. It'll eventually die, he'll buy a new one, repeat this situation, etc...
I'd usually say he doesn't deserve help at all if he thinks like that, but that could be off the mark, he might just be worrying that you'll mess up a very expensive piece of equipment which is understandable when you really don't know how computers work.
Another spam zombie perhaps, but maybe an opportunity to talk to him about the effects of malware and why he needs to get it sorted, even if it takes getting a 'pro' in to do it? ;)