OP didn't say they cared about whether or not the old player would reject the new player, just that they want the new player to get tonnes of CR and thrive where old player has to see it. Sounds more like they hope that new player's presence in the game (and potential popularity) makes the old player uncomfortable, not that they anticipate they'll feel any obligation to interact with them or acknowledge the pairing.

OP doesn't mention new player's attitude directly, but if new player is threading on the TDM and they app despite no input/active rejection from old player, they probably aren't there to ship push. This is apparently character/pairing hate on old player's part (saying they never tag the character, crowing about the cast meeting cap) so new player's behaviour isn't a catalyst there either.

The two clues we have suggest new player is fine and that even if they weren't, it wouldn't have any bearing on OP's feelings towards the other player.