I can't see the point in keeping the Select committee if Markey switches positions.

Usually I'd agree that havin' two agencies with overlapping roles is a waste, but it might be good in the fact that the Select committee and the Energy and Air committee can approach the problem at different angles, and having two agencies might be able to more broadly attack the problems.

If the E&A subcommittee is bogged down (for whatever reason) on certain issues or legislation recommendations, then the special committee can take up other problems in the meantime.

It also would be useful so that in the future if we get another Dingell (God forbid) in charge of one of the committees, we can still have progress in the other committee.

Think of it as a fail-safe.

On the other hand, I can also see how conflict can occur if the two committees disagree.

You'd think that someone who wants a leadership role in the Energy and Air Quality Subcommittee would take a stance on Cape Wind, the the largest proposed off-shore wind farm in the US, which would be off the coast of Markey's home state. It's been tied up for 8 years now in the permitting process thanks to the likes of Bill Koch and Ted Kennedy, and it should've been built ages ago. Everyone knows it, but they're still too afraid to stand up to Kennedy, and oil baron Koch has more than enough money to throw around to spread misinformation about it.

Markey's line has consistently been that there's not enough information about the windfarm's effects or effectiveness (despite the years of research), yet he jumps at supporting the deep water proposal from Blue H, which would use expensive technology that has never been used before?

Typical politician. And groups like PIRG are too afraid to stand up to him on this, even though they support Cape Wind, because they don't want to upset a man they see as an ally by telling him to man up and take a position.
It's all politics. And Markey should do the right thing and support Cape Wind.