Regardless of being peeved or not, it's a lost sale.
It might be a lost sale for AMD in the short term, but, it's also a lost sale for Nvidia, no Gsync monitor sold. And one less Gsync monitor sold means one less person tied in to Nvidia's eco system.
And since AMD's market share is so small, the differences are stacked in AMD's favour. Just random figures to illustrated what I mean.
If 10% of AMD GPU owners currently with a Freesync monitor decide to go Nvidia because of this, then that will be a small loss. Now If 10% of Nvidia GPU owners decide to buy Freesync monitors for the same reason and then change to an AMD card for their next purchase, well that will be a massive net gain for AMD and Nvidia will be losing twice because they haven't sold a Gsync monitor either.