They can't move Chabot instead of Chychrun. Chabot is at the lowest point of his career and is signed for 4 more years at 8M per. If another team would trade for him, Ottawa would likely have to retain or take back a bad contract. Without doing either, he is either untrade-able, or he is only trade-able for a very soft return.
A good activity with players is to ask yourself, if they were a free agent July 1st, would they be able to get their current contract on the open market? I don't think Chabot gets 8M x 4 with a 10-team NTC. Also, his real money AAV starting next season is 9.5M, which will be a factor for some teams as there are quite a few budget teams who do not spend to the cap.
Also, why would Chychrun extend here? The only reason there is a chance he might is because of the hometown connection. Looking at everything else, it makes absolutely no sense for him to prioritize staying. It's a terrible fit on the ice because they already have 3 top 4 LHD. They are locked into a failed roster with little to no way to move out players in trades that make any sense. Chychrun spent his entire career already with hardly any playoff hockey. It is unreasonable to expect him to stay.
Then if he doesn't really want to stay, the ask is probably top 2 D money. That would be 8 years, 9.5M, NMC, signing bonuses. If he wants to stay, the ask is probably 8x8.XX with signing bonuses, and some sort of NMC or NTC.