My previous post was a bit wandering, so here’s the point in brief:
You can’t make exceptions for one thing or another just because you really like them. You can’t say “whitewashing is bad, but I really like this actor, so it’s okay;” this is where whitewashing is happening, so if you oppose whitewashing, this is what you have to oppose. Likewise, you can’t say “alternative casting is good, but I’m a real purist about this one canon, and this character should be a white guy;” this is where alternative casting is happening, so if you support alternative casting, this is what you have to support. If you support something in theory, but not when it actually happens, you’re not a supporter at all.