In the past, Walmart did contribute significant funds to and joined forces with a gay advocacy group, (NGLCC - National Gay Lesbian Chamber of Commmerce). But it seems a backlash from their conservative customers put an end to that practice, which shows what collective action can do.
Forgot to add that WalMart did also contribute 5 % of sales to the Washington DC Community Center for Gay, Lesbian, Bisexual, and Transgender People. But once more, the AFA was on them almost immediately (2007).