From Kurz:
"My understanding of the situation is that while the Flyers are fielding calls on him, they’re not interested in just giving him up for nothing to clear that cap space — but they also don’t have any sort of price tag attached to him, either. Ristolainen, 30, is off to a solid start so far this season, and as a right-handed shot with size and snarl, he could very well be a player whose value only goes up the closer it gets to the trade deadline. Any potential return for Ristolainen would depend on how much salary a team would require the Flyers to retain."
Right now they're on target to have $3M in cap room at the TDL, but they also have the option to LTIR Ellis who is now on IR. By keeping him off LTIR they can accumulate cap room, but once you hit the TDL, there's no reason to continue to accumulate cap room for this season - so they'll have the flexibility to retain/take a bad contract back and make other deals.
This is probably why they're happy to slow walk Johansen, if he's off the books they can accumulate cap room and if the arbitrator rules against them then resort to LTIR to clear him off the books.