...And just when this forum was getting boring too!

Is it possible? Maybe. Without a white paper, or any details its going to be hard to reason about it.

If he's using POW, and he doesn't have a different way to order the chain than the most work branch, it's hard to see how you can have 0 confirmation safety, because forks mean transactions get undone, hence the problem with double spends.

You could have a totally forkless (and therefore double spend free) system if your miners were a static set, but that's a pretty centralised idea.