You could also use another type of work clamp to just secure the pipe into place on your workbench, rather than using a vise. Use what’s available. Clamp it a few inches away from the cut to give yourself ample clearance. If possible, you can clamp on both sides of your cut, but having one clamp a few inches from the intended cut line will make it plenty secure.
The arm strength necessary to use scissor-style cutters is sometimes a little extreme, and it would be easier to just use a saw of some kind. Investing in a ratchet style cutter will make your job a whole lot easier.
