So you actually believe the media that AC Milan decided to abandon the move for Boniface because he is not fit? Personally I don't; I feel it is just an excuse to blow off the deal. If they really wanted him, fitness is something that can be worked on and improved, but I think they had other plans.
Werder Bremen did not hesitate on the deal to get Boniface. Watch the interview.
https://www.youtube.com/watch?v=w8rKa5liEn4You will see that that is a very confident Boniface.
The news don’t looks real because i hardly heard that a player failed medical because most of the player they are signing that do undergo medical are players that are playing from another team before joining any team, and they all did medical before joining the teams and I am sure every team have their own way of checking their players before every match to make sure they are all good before the commencement of matches.
However, AC Milan might have another reason for rejecting the player due to personal reason despite agreeing personal terms with the team. Now he has passed his medical and has joined Weder Bremen on loan. I wish him Boniface well in his career.