Interesting idea... but 95% of the employees who even notice it won't have a clue what it means.
It might be more effective to reduce the fancy oversized font, and replace it with a short phrase, something simple like:
"opencarry.org thanks Starbucks
for supporting the 2nd Amendment"
Of course... it's probably not a good idea to use the ocdo name (in any version) without getting the OK from Mike and John first......
You could always just use a generic "Thank you Starbucks / for supporting the 2nd Amendment."