I don't know if that would be enough to kill the spores, I got some rock from a fellow reefer that had bubble algae and I soaked and scrubbed it with hot tap water then cooked it in a dark tub for about 2 months and a month after I put it in my tank it was covered with bubble algae. There was no bubble algae in the tank prior.
Absolutely right...one of the roles of spores is to survive extreme adverse conditions. Like drying out and baking in the tropical Sun, even to survive time in animals digestive systems. If you want to start rock free of spores a muriatic acid bath is a must do to remove the surface layer of rock that spores may be embedded in (the spores may actually be impervious to the acid too but can be physically sloughed off).
However the other way of thinking is that all of these things will eventually get into your system anyway and a well balanced system will prevent any one thing from taking over. Back in the day...we filled our systems with real live rock from the ocean that came with all manner of things in it from algae to gobies and small eels so the micro fauna was wild, varied and out of our control.
I don't know if there is a "right" answer...there are so many brilliant "natural" type Reef systems but most of the hardcore SPS growers now tend to be done in the tightly controlled artificial "better than nature" model ie Darrylv's tank or many of the Zeo systems. Like so many things, I think you need to choose a path and not deviate too far from one or the other.
