If cut post 6/1 2025 I think that makes 2025 a bit easier as that drops his dead cap from almost 50m for 2025 to ~18m, but that pushes ~31m in dead cap on to 2026, which is still a ton in year 4 when you're saying they should start winning. I almost think it's just better to cut him pre 6/1 2025, take the 50m dead cap hit (which is still less than what his cap hit would be that season) then be completely free of his contract by 2026.
I just don't think the "Russ is Garbage" scenario is actually a good one for the new coach. A good coach isn't going to want to deal with that cap handicap unless the FO does an incredible job drafting to compensate for Russ' cap. I view that more as 1 year to prove yourself after a few years of being handicapped, rather than 3 years to prove yourself. And even though FO should take the most of the blame, 3 years of losing is still going to rub off a bit on the HC in terms of public/media/player perception. Extended periods of losing can also make it tough to build a good culture in the locker room.