Regardless of who is right or wrong, Joe is an entertainer - something he has stated many times in his videos - and is representing nobody but himself. How he acts on Twitter is really up to himself. He didn't react to it particularly well, but it's only his own reputation at stake.
Dan, on the other hand, is a professional journalist representing a multinational company. His Twitter profile says "IGN's Reviews Editor", his profile links to ign.com and his profile on IGN links to his Twitter account. He really shouldn't be acting in this way on Twitter - not on that profile, at least (he would be free to create a profile not mentioning who he works for and do what he wants there).
This doesn't apply to just games journalists either. If someone has a prominent role at a company and their Twitter profile is linked to said company, they really need to take care about what they say.
Dan, on the other hand, is a professional journalist representing a multinational company. His Twitter profile says "IGN's Reviews Editor", his profile links to ign.com and his profile on IGN links to his Twitter account. He really shouldn't be acting in this way on Twitter - not on that profile, at least (he would be free to create a profile not mentioning who he works for and do what he wants there).
This doesn't apply to just games journalists either. If someone has a prominent role at a company and their Twitter profile is linked to said company, they really need to take care about what they say.