I think the bar for being "a giant piece of shit" should probably be a little higher than the act of getting a coffee. I mean, if customers are giant pieces of shit, what are the Starbucks executives? Galactic boulders of excrement?

Jokes aside and more practically speaking, I think it's more productive to urge people to consider patronizing their local cafes - or learning how to make good coffee at home - instead of trying to shame people who probably don't know or honestly care that much about random labor disputes for getting a coffee. Beyond being more positive, it's less likely to annoy people into spite.

I would say go use it if you have a gift card. They already have the money, might as well cost them some product instead of giving them an interest free loan.

I'd suggest having them remake it a bunch if that didn't fuck over some poor barista. Although ... that would be pretty funny for the pro-union stores if they were in on it.

We all have various things going on in our lives, and we often only find out about something after the fact. If you blame people for being late to the party, they'll just skip the party entirely rather than deal with your misplaced ire.