Frankly I don't know how this so called Christian found out which bakeries were owned by gays and which ones weren't. The story does say that at least one was in Ireland, which isn't exactly the US, now is it?
For the me the big difference is this. Couples wanting a cake for their wedding just wanted a cake not an editorial page. This individual deliberately wanted to order a cake with a written message that presumably didn't gibe with the beliefs of the shop owners.
To be honest I'm not quite sure how this works. We're guaranteed free speech in the public arena but is it the same for a private business? Usually if you're too obnoxious in somebodies store or shop they'll ask you to leave. That said, there's no need for the folks running the bakeries to be insulting, threatening or anything like that. It's not only rude it doesn't help your cause.
It's a mystery and I wish I had an answer.