I have no spoilers so i do not know who Ben's man is on the boat. Can this be answered without using Spoilers? I am just theorizing. But this could be a spoiler to someone so i am putting it under spoiler. Spoiler
I was thinking that if Michael is the man on the boat then wouldn't he be really evil? First he kills 2 of the lostees and now he is trying to stop the boat from getting to the island. Destroying the communication room, etc. The boat means rescue to the lostees (at least 6 of them).
You are making a lot of assumptions... MIchael could actually be helping the Losties, we still don't really know what the boat people intend to do with the island.
It's Ben vs. Widmore, the Losties are just in the middle of it, is there really a good/evil side?
Maybe Ben lied to Michael and manipulated him into thinking what he's doing is helping the Losties, can you really blame Michael? Even chuck norris would get manipulated by Ben, especially with Michael's guilt, Michael would do anything that he thinks will help/give him redemption.
And remember we have NO idea exactly how the oceanic 6 get off the island, judging by the future it's obviously a pretty fucked up situation. The boat could or could not represent rescue for them... one things for sure, it doesn't deliver an ideal rescue.