Welcome to the forum. The subforum about rules queries is called
"You Make Da Call", and a mod will probably move this thread there.
In answer to your question: they're treated as arriving from reserves for all applicable rules. Interceptor weapons can fire upon units arriving from reserves. Therefore, yes, the Interceptor rule can be used against summoned units.
EDIT: Just remember that most summoned units are ground-pounders, and most Interceptor weapons (excepting Tau) are Skyfire. In those cases you'll be firing snap shots.