Yes, it's a unique situation, but the key question is - what part of that unique situation entitles the Knights to essentially a free compliance buyout and Lehner to have his contract terminated but still get paid in full? Why isn't this either a typical contract termination or Lehner going to LTIRetirement?
Because Foley was willing to pay 4.5 million he didn't have to.
Whether he did it out of the goodness of his heart, for good PR or to avoid bad PR, or because he's old and doesn't want his conscience eating at him with Lehner in his current situation, you can debate his reason.
But Vegas would get the LTIR gone regardless, he didn't have to pay to get out of it, the breach already happened.
If other owners in the future want to voluntarily pay guys whose contracts they can terminate without paying anything, they can think about it.
If other players want to go through alcoholism, have multiple, well documented mental health related issues over a period of many years, get into massive debt whereby they won't get 80% of the money anyway while also being injured and out of shape, all in an attempt to get paid the last year of their deal (which, again, they won't see most of in their pocket) without showing up to fail a physical...
I guess they could try. Awful lot to go through, though.