[SPOILER]
As far as anyone that noticed him being gone (and I think there are a couple of references) his accursed master put him in that trap, that is what he has told people.
However, Tizzy never really talks about his accursed master and never has to go visit him, and in fact, Gastrope’ is currently his accursed master, and there can be only one (Accursed Masters are all Highlanders)
So either Tizzy killed his accursed masters within the last 10 years or so, or he was lying about the cenobyte trap to cover his disappearance.
I would have to check, but Tizzy reappeared about a decade ago, after being gone for twenty to thirty years.
[/SPOILER]