I’m super pro-union, and strongly support the unionization of the Norfolk workers, but I should acknowledge that this looks like a pretty reasonable response from Costco that’s far cry from the whiny, hostile, threatening responses we’re seeing from the likes of Amazon and Tesla. (absent any other information about the situation).
If you don’t want your employees to unionise, you should give them great conditions, minimising the benefit of unionization, then not sook about it if they unionize anyway - which is exactly what appears to be happening here.