Kevin,
That workpiece is actually very secure in that fixture, and seperation of the 2 is highly unlikely. You do run a risk of breaking the workpiece if you force the cut. I don't worry too much when I'm cutting due to the fact I have a faceshield, gloves and shop coat on while doing this.
I think I need to work on my band saws rub blocks and maybe use a wider (depth) blade. It seems to have a mind of its own whether I'm cutting freehand or using a fence/ miter/ jig. Maybe a new one may be the order of the day:w.
Jerry