Your surgeon is a respected ABPS-certified plastic surgeon with many years of experience. Since I work in the same metropolitan area, I am familiar with this recommendation, which basically involves putting pressure on your implants to flatten them slightly, causing the pockets to stretch somewhat. This is designed to reduce the incidence of capsular contracture by mechanically keeping the implant pockets slightly bigger than the implants themselves. That's pretty reasonable, actually.
But not without knowing that your surgeon also utilizes an axillary incision, so there is no worry about a periareolar or inframammary (crease) incision being stretched open, or contaminated by lying on the dirty floor.
My own recommendations differ somewhat, and I avoid the armpit incision because it is in a warm, wet, bacteria-filled area that moves around with every arm motion. Bacterial contamination of the implant (even with use of a Keller funnel) is somehwat higher with an armpit incision than with a crease incision. This increases the risk of capsular contracture and reoperation for capsulectomy, which cannot be done through this incision. Periareolar incisions have the same issue, IMHO, because the breast ducts are filled with bacteria that the implants must pass through on their way to the pockets. And no one sees the crease scar, but some armpit scars are visible when in a swimsuit, sleeveless top, or strappy dress! I think the slightly higher risk of unsatisfactory scars and higer risk of capsular contracture, not to mention what I feel is a higher potential for implant malposition, is NOT worth trying for no scars on the breasts. And, if a revision is needed, a crease incision is often (usually?) needed, so who wants 4 scars?
Also, why not simply create a surgical pocket slightly larger than the implant in the first place, rather than trying to achieve this (or maintain it) with implant compression? I instruct my patients to perform implant displacement exercises several times per day in order to break up any adhesions that might form in the already-open larger pocket. Once healed, the pocket remains somewhat larger than the impalnt, keeping the breasts soft, and the implants slightly mobile, such as when reclining, where the breasts slide towards the side and flatten like normal large(r) breasts do. These implant displacement exercises can be done clothed, standing, reclining, and take only a few seconds per breast. Easy. Effective.
So, I don't think there's anything "wrong" with your surgeon's recommendation, it just strikes me as possibly inadequate, maybe uncomfortable, awkward to perform (especially down the road, since healing and scar maturation takes 6-12 months), and potentially dirty (depending on your housekeeping talents). That being said, you should always follow the advice of the surgeon you choose to perform your surgery, since it is s/he you will go to if there is a problem later!
But didn't your surgeon explain his reasoning to you? If no one on-line agrees with this, will you fail to follow his post-op protocol, even if it does sound a bit wonky? Please talk to your surgeon! Best wishes! Dr. Tholen