Ah for sure, but you can see my point though right?
If a team makes 500 against India then having Sehwag does NOT help. All he does is make the Indian innings shorter and unless India make 700 in reply they have little chance of winning so his scoring rate is more of a hinderance than a help. So a Sehwag is very handy if your team can get 20 wickets but just needs a bit more time to do so. But if your team can't get 20 wickets then you are better off with a guy who can bat longer.
I guess my greater point is that scoring rate in Test cricket can be a bit overrated. Because unless you played on the 70/80s Windies or 90/00s Aussies then you are going to have to face a defeat fairly often and you need to be able to adapt to those circumstances and fight for a result. Sehwag can't. His 2nd innings record is awful. I guess though that an all time XI wouldn't be facing defeat often, so perhaps his selection is a master stroke