Lots of people jumping to the conclusion that they were fired because of the public backlash. That's fine, and may be correct.
I think it's more likely they were fired for not abiding by internal regulations on communications with players, as said in the ArenaNet statement. If there is an outlined process/rules for interacting with players (even on a personal twitter account) as an employee of the company, you sure as hell need to abide by that.
Instead of assuming this is ArenaNet "giving in to GG" or similar, consider that they are a company and need to uphold their own rules and expectations of their employees in order to keep the ship afloat. Regardless of your opinion of this situation, both employees acted unprofessionally, and those aren't the type of people you want interacting with the public.