I don't think so; in this case, the `Dispose` method should be called explicitly by libgit2, and never by any caller.  I think that decorating with `IDisposable` suggests to the caller that they could (or worse, should) dispose it when in fact they should not.

That said, I think a better name is in order.  I used `Free` in the registration class to avoid this exact ambiguity; I didn't really notice this one.  This PR has been hanging out for so long that this all looks foreign to me.