It'd be dumb for an immortal to make an enemy of someone they can't kill, but who can kill them. That's why Quanxi avoids conflict with Denji.
Even Yoru said it, she put Pochita down a bunch of times, but lost once and got eaten. It's a pointless fight to pick unless you're looking to get eaten like Aging or Makima. Or just plain dumb like Yoru.