Last year I recovered from a torn (not through) biceps tendon. A month of PT did it for me-those folks knew what they were doing. The scary part was the OS told me that if it had been severed, there wasn't much that could be done. I had never heard of that and it scared the hell out of me. Didn't do any shooting during this most of the time this is time, getting better was all I had on my mind.
With respect to a biceps tendon rupture, the structure that is most often torn is the long head of the biceps muscle/tendon unit. What this means is that there are two connections at the upper end of the muscle where it connects to the skeleton on the shoulder blade and humerus bone. If the long head is torn, the muscle and arm still function (i.e.; you can bend your elbow to lift things). Repairs are usually performed on "younger people" since in most cases "older people" don't lift and carry as much. In its infinite wisdom, the medical establishment makes the decision for you that you that the cost of the repair and rehabilitation is not necessary for old farts, since they aren't as active and in need of strong bodies. Unless you tell them otherwise. The reality is that most of us over 60 are fine with that. So my suspicion is that the surgeon could have repaired the tendon had it ruptured, but felt that doing so may have been troublesome and perhaps nor necessary for you to be able to carry on.
The other end of the muscle, where it attaches to the forearm below the elbow, is a different cat. That has to be fixed or the elbow ain't gonna work well at all.
Tendon repairs in general in the hand, wrist and fingers require that the orthopedic surgeon and Occupational or Physical therapist be specially trained experienced. There is always a balance between getting the tendon moving enough to avoid scar tissue gluing the moving parts down, and alternatively risking rupturing the repaired tendon with too much movement/stress. For surgical repairs of hand and wrist tendons, I would opt for local anesthesia so that the surgeon could test my ability to move after the tendon was repaired. Too short or too long leads to trouble. If/when it's me and my paw, believe me the doc and I are gonna talk about it.