No, if SOME pools would change the rules.  But we are considering the case where ALL pools fix the rules (the same ones, or the same change).

You are just printing what your local full node would tell YOU.  But if all miners are in agreement on the rules (old ones or new ones) - that's the case we consider - then there's no orphaning.  Because only miners can orphan blocks, by building on other blocks.

(btw, strictly speaking, an invalid block is not orphaned but rejected: the definition of orphaning is a VALID block that is not built upon ; by definition, blocks in the chain are valid).