I signed it. Just because you make something for Linux doesn't mean you can't charge for it.
As a matter of fact, there are already Linux based editing programs for professionals (like Piranha). But at 5 digit pricing that's just not in everybody's budget.
Many if not most visual effects companies already work on Linux, usually using custom programs, or non-free programs like Combustion, Mental Ray, and Maya. So yes, Linux is a very viable option for creative professionals.
More info on VFX/editing on Linux:
http://linuxgazette.net/147/rowe.html