Actually it is logical for Google to contribute funds to SOPA sponsors, if influence is indeed being wielded through dollars then this is one of the best options to counteract such legislation in the shorter term.
Edit : If I were trying to disrupt SOPA, then one of the most effective ways to do so would be to raise a large conditional donation for Lamar Smith predicated upon him withdrawing support from SOPA as well as raising his voice against such measures. After all no argument will be more persuasive in redefining his view of the internet than a large a large check in his name.
Given how this impacts the future of the internet this might be the best investment anyone can possibly make.