Prem Rawat and the Divine Light Mission are legitimately connected to Hinduism. They might not be main stream in their thoughts, beliefs, or teachings, but they still have a connection to real Hinduism. Just like how Christianity has many different branches, so do other religions. It doesn't make them any less Hindu.
Every religion has its offshoot sects that bend the original tenets of the mother religion. As long as the beliefs put forward in these sects are not harmful to humans, animals or plant life, they do have a basis in the religion that spawned them. In this case, in Hinduism.
All religions spawn offshoots of themselves that are more or less legitimate. These two may be less legitimate, but by the same token the Hinduism they come from is one of the religions with more sects and divinities than most. So they can be connected, but not in a way that is helpful for a lot of folks.
I do not believe Prem Rawat and the Divine Light Mission are legitimately connected to Hinduism. I believe the teachings and belief system between the two are too far apart to draw parallels. The tenets and beliefs upheld by the Divine Light Mission shouldn't be considered solely linked to Hinduism.
The Prem Rawat and the Divine Light Mission are not legitimately connected to Hinduism. If they were, then the Prem Rawat and the Divine Light Mission would be getting a lot more support then they are right now. This proves without a doubt that they are not legitimately connected to Hinduism.