Hey Blue dog,
congrats on 10 weeks! I probably would have went to the store for him. But before I had, I would have definitely done two things:
1- checked my spiritual fitness. Am I ok to walk into a store for the purpose to buy booze.
2- If I felt strong from #1, then I would have set a boundary and told him that this is a one and only time. Hopefully this situation won't ever happen and if it does you've already given him the answer.
I take my sobriety as my number one priority. Without it I don't have friends, family, work or ability to do a "solid".
Good luck and many prayers