I'm not surprised he'd check after someone says the game sucks, due to the 100,000 pirates trying to connect to multiplayer who ruined the early multiplayer experience and were directly responsible for many of the poor reviews that Demigod received in the first few days.
That may not have been your intention - and your brother may really have Demigod (I don't know either way), but I think you managed to stomp on a sore point, especially when you went beyond stating your dislike and said that the reviews all said it was bad (even though the reasons it got panned had less to do with the game's quality and more to do with, well, pirates).
Also, it's easy to forget that this subforum (PC Gaming) is one of the off-topic Stardock forums, which means it's available from everything from Joe User to Window Blinds. I'm reading it via GalCiv 2, although lately I'm just as likely to pick it up from Elemental.
(I don't have Demigod and don't plan to purchase it - I'll get Sins first if I get anything outside Galciv 2 and Elemental at all. I just kinda sympathize with Brad on this point)