JPK,
Yes, in a case where the main sear has accidently been released, it is possible that some types of intercector could release the tumbler from its "caught" position with a pull on the trigger, and this may well still ignite the cartridge.
These are the types that use a second sear which catches the tumbler before it has travelled very far on its way to the striker.

There are however, other types of interceptors which actually block or catch the tumbler when it has travelled much farther toward the striker, and even if they could be released by pulling the trigger,(some cannot) their remaining energy and travel would not be sufficient to ensure ignition of the cartridge.