We know that Dali only fell during RotCH just below Lu You Jiao was assassinated by Huo Du.
Which meant that Dali was still fighting a war and 1Deng, his 4 disciples and Scholar Zhu chose to ignore that and instead helped on the Xiangyang front.
Isn't it a little ironic that they are showing so much "patriotism" but not towards Dali? A little weird none of them returned to aid Dali? Or did the other 3 disciples returned (Wu San Tong didn't for sure)?