You left yourself open for this, so here goes
Here's what I think you should have said:
"Had I known this, I would have considered purchasing Apple a bit more and are now relectant to purchase any future Apple products."
Really. Apple products are a small fraction of PCs out there. And Apple is notorious for trying to keep their ecosystem closed, or at least difficult to enter. What did you expect? I don't think Tamron's attitude is unreasonable. Given how common they are, surely you must know someone with a Windows machine.