But his teammates didn't get ghosted by the HC, they hadn't had zero negotiations on an extension, so the circumstances were not the same for his teammates. And you are crazy if you don't think he didn't want to ball out for a big contract, but when week 10 rolls around and it is evident the HC is game planning you out of relevance, to say it wouldn't affect you is intellectually dishonest, unless you are Saint Modo. Are you Saint Modo?
He could have handled it better, but there isn't a person alive that would not be affected be being marginalized on the field and basically having the HC take millions out dollars of his earnings potential because of some petty whatever the hell was in Nagy's pea brain.
I would go to him and have a very frank conversation as GM,
"Allen were letting you hit FA, we wouldn't mind having you back for the right price, but we have to have a talk about some of your play effort late last season. Some things looked uncharacteristic of you, but they are unacceptable for us moving forward, can you explain what led to your effort issues last season?"
Depending on the answer you either consider him or thank him for his service and move on.