They are doing this for liability purposes and protection of their employees. It is the smart thing for COSTCO to do in the short term. Give it a rest. The ban will be lifted in time.
Costco ia doing it because the company is run by leftists and they want to virtue signal. Costco has a long history of leftism. Go look at their twitter. The last tweets were regarding a Costco ad “accidentally” on Breitbart.