A "competitive advantage in the capital market" means something that VCs require from the companies they invest in, like "strong founder team" and "established product market fit". I don't see a lot of VCs demanding or preferring unionization among the companies that they invest in. Do you know of many VCs that have pro-union stances? Even if there are some, I think it's fair to say they're not the majority, hence it's likely a unionized business will not have as good of a capital-raising opportunity as a non-unionized business.