I have the performance package with the 21" tires. I got a screw in a rear tire right in the middle of the tread. Easy fix I thought. WRONG! Took the car to a local big box tire facility and when they pulled the tire it had the acoustic foam! The manager remarked that he didn't even know Perelli made an acoustic foam tire. He said they cannot patch it because the foam is glued into the tire and it would ruin their tool. So he said I needed to contact Tesla because he could not order that tire. So I called Tesla roadside service and they said the foam tires cannot be fixed and it would cost me $462.50 for a new one. I just about blew a gasket. My front one that I destroyed a year ago was only $325 and it was truly unusable. This situation is I have a simple screw puncture. So I read an obscure thread on here about taking it to a "small shop" and get a plug. So I found a hole in the wall small tire shop that would do plugs. However when I got there the owner said "we can patch that tire! We have done it before on Tesla's. I explained what the other guy told me and what Tesla said about needing a new tire and he laughed. So I watch in delight as they carefully pulled back the acoustic foam, removed the residual glue, put a bonafide patch on and the reset the foam with some of their glue. I looked perfect when done! Total cost... $25. Your results may vary.
I forgot to mention this, but this was brought up in the past when Tesla launched with the ContiSilent acoustic foam tires. Many places claimed they can't be repaired, people brought up links from Continental that had official repair instructions, and suggested printing them out and handing to any shops that want to argue they are not repairable (as a side note the same documents did point out run flats were not repairable)..
One example here but the link is dead.
Tires Cannot Be Repaired?
I found working links here, basically it's as you mentioned. Just cut out and pull back a section of the foam and do the repair as normal. The manual didn't even suggest putting the foam back.
Tire Repair
I wasn't able to find a similar document for Pirelli (maybe because they are relatively new to the game), but I did find a document from REMA TIP TOP (same organization that wrote the continental document), that does mention the Pirelli PNCS tires.
http://www.rematiptop.com/assets/tech/trm/Reference/Sound-Suppression-Tires-Repair-Guide.pdf
I did dig further and it appears the condition for denial of repair is related to both the PNCS and the speed rating (yours are probably W rated).
Pirelli has the following warning in the warranty:
"PIRELLI TIRE DOES NOT ENDORSE:
1) The use of tire sealants in Pirelli tires to repair, even temporarily, a puncture;
2) The repairing of V, W, Y or Z Speed Rated tires;
3) The repairing of Run Flat or PNCS tires."
They have a road hazard warranty as a result for Run Flat or PNCS tires, due to their policy.
https://www.tirerack.com/images/pdf/warranty/PI0717.pdf