Perhaps it's because I'm tired and I'm not understanding correctly but what is the practical difference between Stallman's suggestion and simply abolishing software patents?
He says you can't revoke existing software patents legislatively, so abolishing the ability to get NEW software patents would take 20 years to fix the problem (for the existing ones to expire). By saying those existing patents can't be enforced the problem is fixed now.
Another difference suggested by Stallman is that there is no legal definition of non-software patent, and software patent.