If there's any indecision, it seems to be coming from Marcus's camp. He doesn't want to be out for so long, yet that's part and parcel of recovering from injury and surgery.
The club's medical staff have suggested surgery. Ole wants him to be optimal and healthy, that's pretty obvious. Ultimately, it's up to the player because it's their choice even if they are getting all the advice from the club saying do the surgery.
I hope that Marcus is not hesitating to have surgery because he's afraid of the recovery timeframe and what it means to get his place back into the starting XI. His place is genuinely up for grabs with and without him because the competition for places with the addition of Sancho and continued emergence of Greenwood and Amad, Martial is still here, etc.
Marcus has not engaged in challenges and pressed as much as his teammates because of his injuries. He cannot afford to engage and work so hard off the ball without the lingering risk of further injury.
A healthy and well rested and clear minded Marcus is what the club needs.