This is what's known as hedging.
If I get pulled over 10 times by 10 different cops, and I offer each one $100 to let me off, and only one of them takes the bribe - the other 9 don't negate the fact that one guy took the bribe.
"No your honor, I just like giving money to police officers whenever I meet them. See, its just random chance that this one guy let me off. Clearly it was on the merits of the situation, not because my money influenced him."
Cops don't make the laws of course. Otherwise you'd be allowed to bribe cops.
Lamar Smith (R TX-21) Support: $277,350 Oppose: $41,000
I see some other Judiciary Committee members up near the top with similar very high support/oppose ratios and I think it's been fairly supportive of the bill overall. Then I looked up some of the more notable opponents: Pelosi & Issa. They have 2-1 and 10-1 ratios (support/oppose) in spite of being opponents.
I think looking at the list of industries that are SOPA supporters is more interesting. Exactly why do some of those industries want to support SOPA? Here the oddballs industries on the list: auto repair, animal feed & health products, confectionery processors & manufacturers, optical services (glasses & contact lenses), & tobacco & tobacco products. Why are they on there? My best guess is that lobbyists are involved somehow.
Counterfeit products, perhaps?