Do blocks= txs?
You see, I don't have a choice on whether to relay a BLOCK but I do have a choice whether to relay a single TRANSACTION.
So, an analogy:
If I deliver packages and letters but a letter comes through witha giant dick drawn on the face of it. I can mark that letter as "Undeliverable" and send it back to sender.
BUT if that SAME LETTER is in a box with a bunch of other letters I MUST deliver the box even if there are bad letters inside. I am fine with this as it doesn't break my delivery rules.