It occurs to Dirk, as he's being toted around like a toddler, that he could use the doorway to make Hythlodaeus' life harder. It also occurs to him that his hands are free--he has six Pokemon he could deploy at any time, and only two of those Pokemon are likely to harbour any bias in Hythlodaeus' favour.

In the end, though, he does the maths and decides it's not worth it--a decision validated moments later when Hythlodaeus lets him down, although not without one final, strangely affecting gesture. He's literally queasy after that. Which doesn't stop him from (and may, in fact, be a motivating factor in) digging in his heels and making a stand, both for his dignity and his decision.

He does not, in fact, go settle in with the Ponyta. He doesn't even move an inch from where Hythlodaeus delivered him.

"This conversation is over."