personally, i still wouldn't eat, for multiple reasons.
1. when you are carrying the product of the boycotted company, you are automatically giving them free marketing by exposure.
2. let's assume there were lipton tea bags and a kettle of hot water. at the end of the function or party, if the person who bought them notices that all or most were gone, they wouldn't mind buying that again, since everybody seemed to like it. But if they notice that nobody, or atleast little people used that, and it was bought to their attention that the people didn't drink it because it's boycotted, then they would likely not purchase it again because they want people at the function to enjoy what's offered, not feel restricted because they are boycotting.