>>10
Remember I mentioned this for an 'ideal' (for a given value of ideal) world.
Please also note that if the law (explicitly or implicitly) require me to hire rat exterminators, and that I finally get the law to explicitly not mandate rat exterminators, then I can fire all of them no matter what they've been advising all this time.
Big companies have legal counsel other than patent lawyers. Those can advice on the legal matter of outlawing software patents. Their payrolls are not at stake. If there is an opportunity window to get rid of software patents a simple cost-benefit analysis can tell you if it's worth it to go ahead and bankroll lobbyists and lawyers to then fire the software patent lawyers, and those would have little say in the matter.