Eh? He had the preferable call this race. Was on the hard tyres at the start so pulling in after 20 laps to change to the softs would have been disastrous.
Actually, I'd say this is the first race of the year a 2 stop for 3 sets of tires would have worked VERY well. 22seconds in the pit lane, - about the 6-7 seconds that straight normally takes, its a VERY minor pitlane, and when his tires were on he was very fast, the second everyone else came in for tires the guys who had been ahead and the red bulls were all a second a lap faster on decent tires(well about a half second, but Hamilton was previously a half second faster than them). If he was losing a second a lap, for 10-15 laps, it would probably have paid off to be on the best tires each time. It would also likely have twice in the race pitting at the right times, meant he could drop back out in fresh air like Button did. It could basically have been a wash on tires vs pitting for a fresh set, but being better fresher tires obviously makes a huge difference in overtacking traction and obviously more pitstops gives more chances to pop cars into fresh air for a good bit of speed.
Unlike Button, in fresh air Hamilton could really have gone insanely quickly. Let say Hamilton did what Button did, went in before the rest by 10 laps, frankly running around in that free air he could have gained a LOT of time back on Alonso/Massa/Button and by the time they pitted been miles ahead, still in fresh air, got a pitstop ahead of Sutil and Kubica and stopped again and raced to the end.
Last race a pitstop cost you what, 43 seconds was it in the pitlane, compared to 15 seconds on track, it was huge, 22seconds this race, it was a close call.
Button with fresh tires, in fresh air, ended up behind Hamilton after his stop, even though Hamilton was on worn tires and in traffic most of the time.
Thats all ignoring the fact that I was also including the absolute joke of a decision by McClaren and Ferarri to not go out and put in a simple decent time in early in Q1, had they done so the McClarens could well have started from the front, well Hamilton could have been on the front row, possibly even pole judging from his pace in rain in general and his speed in practices(ie fastest in all but one session where he was 0.017 behind Webber wasn't he). Button would probably have been top 6 but very unlikely to be in the top 2 rows IMHO.
I also think if he had to go 1 stop, it would have worked far better for him to do 15-20laps on softs and the rest on hard tires.