Synthetic blend vs regular oil

“You better hope you never need any warranty work from this dealer…You are on their “no fly” list now…”

Ditto!
After throwing that hissy-fit over an issue that is truly a NON-issue, the OP should really avoid the embarassment of ever returning to that dealership. If warranty work is ever required, find a different dealership.

And, rather than throwing a hissy-fit the next time that a supposed issue arises, I suggest that the OP check with this forum before he/she makes a spectacle of himself/herself.