Dick's has a history, if I remember correctly, of being on the left side of 2nd Amendment issues. I don't recall the exact things the company has done, perhaps not selling modern sporting rifles? Whatever it was I quit buying anything from Dick's. I still go in the stores to look around and have found items I wanted, I just note the item and buy elsewhere. Hardly ever do I find that Dick's has the best price on things anyway.
"Don't shoot the messenger" applies to the store personnel- they don't dictate corporate policies.
I understand the OP's frustration but berating clerks and managers for corporate policies makes as much sense as berating a LEO for enforcing laws enacted by the legislature and governor.
"And three, be nice." Dalton in the movie Road House