But a variant on our timeline would still look like Loki
why would branching a variant timeline turn him into a Hulk Loki or any of the other very different Lokis?
A timeline where Loki hit himself with gamma rays to try and get payback against the Hulk? The key thing though is it's not linear. The variant may be from birth (born a woman) and the branch happens immediately. Other variants may come from choices, like my initial point.