It's what Henry said. I'll believe him on his own motivation when it's so clearly stated.
He also said he was going back to stop Abaddon. Do you believe it's accurate to characterise him with one motivation and not both?
And he seemed resolved to his cause.
Until he changed his mind, yes. And Larry had no such bias. Which is why I can't feel I know the organisational bias--two wouldn't be a pattern even if they agreed with each other.
Dean in the herbal shop hit Henry who was attempting to do blood magic.
I have to admit to a very "fight amongst yourselves" attitude to Winchester family disagreements. If Sam and Dean ever hurt a third party in order to save each other, an innocent, I mean, then I will worry and call them selfish. I totally cop to that bias--it's no way to live in the real world, but that's probably why grandpappy thought they were apes. Because they only way he could stop him long enough to convince him that he was capable of stopping Abadon, plus this way he gets to keep his brother, since unlike what you said, Henry wasn't going back to save John. He was going back to parent him (not unimportant or inconsiderable at all--but the default narrative bias is always going to be "this way isn't that bad--we already lived it anyway so let's call it done"--he's presenting Henry with a known quantity, and saying "preserve this and save my brother instead of rolling the dice."
Do you think that time is still malleable? Are we in a My Heart Will Go On universe still, and not reverted back to The Song Remains The Same? I don't see any explicit plot happenings that would have switched it back, but I suppose they could justify it with a heaven-restoring-order explanation or something.
Which makes me wonder another thing--can they make more angels? Or can Heaven never recover from what Castiel did? Like, did he break Christianity? And time travel? Not bad for a nerdy dude with wings.