Just business. They have to defend their trademark or it becomes invalid. Bad idea to name a product that similarly to a well known brand. You think you could market a Sevens Up beer with seven hop varieties in it just because it's not technically the same product? What they could have done instead of throwing a tantrum is use good business sense when choosing the name or work out a deal.
This is bad for all craft brewers.
This is bad for all craft brewers.