Yes, adopted siblings are real siblings, I never said they weren't but they aren't blood which specifically means genetically related. It's an incorrect usage of the word and doesn't make sense in this context. Thor and Loki aren't even the same species.
As for the real Thor never saying anything like that, he once ripped off Loki's head and wore it as a belt accessory, so let's wait until he finds out the truth about this Loki before saying what he won't do.
Maybe more involvement from doctor strange is needed? Because he was originally going to cast the inversion spell with SW, but doom ended up doing it instead, and I've been wondering this whole time if that had something to do with the results.
Wouldn't Strange be inverted too, and unlikely to want to help reverse the spell?