GoDaddy is a powerful and monied entity that has been caught paying money to convince the most powerful and monied entity in the world, the United States Government, to implement a set of rules that would generally make it easier for rich corporations to silence poor critics. The GoDaddy boycotters are not bullying the SOPA supporters.
The GoDaddy boycott does have a certain amount of groupthink and mindless sloganeering in it. Perhaps this is what you mean when you say "bullying".
GoDaddy tried to recruit the largest power in the world to help silence the smallest, and you find lobbying others to boycott them "piling on" ?
You say "GoDaddy is entitled to their opinions" but remember, GoDaddy spent money to make it easy for you to have your opinions removed from the internet. They didn't just "express their opinion" that a corporation should be able to shut down critical sites just for asking, they set about to make it happen. They engaged in no dialog or conversation with you, they just tried to get it done.