In general, I’d like to see secret service protection for ex presidents limited to only to basic everyday security. Their homes, offices, daily commuting, errands, family events, etc. the kind of stuff that any regular private citizen has to do.
Anything above and beyond that they should have to arrange their own security services. No one is making private citizen trump hold rallies and invite throngs of people to gather around him while he stands up on a stage, most of us don’t do that, and if we do we’re certainly on the hook for security if we need it.
Now being a presidential candidate, he’s also entitled to usss protection within 120 days of the general election, which I suppose I can agree with, and that would have kicked in for him on 7/8, so a few days before the assassination attempt, so I guess this might still be their mess to deal with if we think they should have to provide security for campaign events.