I think that the disconnect may be that he said "whatever" personal differences. That's not the same as saying "his" personal differences. I think Hosken was leaving open the possibility that there may be no personal differences.
I also think that the nature of their relationship is fair game, although as is often the case we don't have enough inside information to do more than speculate.
Personally, I would have let him go out for the 4th. From Rocco's perspective, either Gray would perform (which would have been great for the team and the fans) or not perform (which would help in the future by reducing Gray's repeated unhappiness when Gray feels that he was pulled too early).
Drama between people who are on the same team tends to fester..