I love your idea.
The old fashioned broadside still has a role, too. Post dozens of sheets photoshopped with Starbucks logo all over town on light posts and walls. Say “We care about our neighbors. We are offering free coffee and pastries of your choice to all this week.” Pass these out to derelicts,too.
Homeless and young people arrive and get furious over denial of the free stuff. Remember every week there is a violent outburst at a McD or other fast food place (manager scalded by hot coffee thrown in his face by customer in argument over prices etc.)
So often the left is able to isolate and focus punitive retribution on conservatives who have the courage to lend voice to their beliefs. Starbucks presents an easy, ripe target for some overdue political payback.