I don't like the "have to share" either, although that comes up more when we intentionally play with other kids on playdates and things like that. I actually don't think he NEEDS to share, but it feels politically incorrect to say that out loud!
When I was nannying, I always told the boy that he didn't need
to share, and no one had the right to take his toys from him without permission. Sometimes when you share, your toys get broken or lost. However, I also followed that up by saying that it was, however, nice
to share, and sharing his toys would make other kids want to play with him and be friends with him. If he didn't share, most kids wouldn't share with him, and he wouldn't have as many friends. In the end, it was his choice whether or not to share, but he needed to accept the consequences.
Of course, he was older than two when this policy was in place.