I read this on the BGG forums and relayed the info to my group. I was explaining the game to a new player and I usually add in things that a cylon or human would do, just so the player isn't coming into the game completely cold. When I explained that humans love the XO card and it's smart to not XO the next player to go she asked, "Why?" Aside from, "Uhhhhh… the next player might be a Cylon," I forgot why. I remembered the method, but forgot the reasoning.

Is it because if they are a Cylon, then they get two actions run amok before revealing on their turn? Was there another reason?

Pretty much. It allows a clyon to "soft reveal" by making a delebritly harmful move such as throwing civves at raiders, wasting a nuke, or executing someone without the risk of being brigged/executed and losing their reveal ability when they "hard reveal".

I am not sure I would say "never", but the more someone is to your "right" the slightly safer they are to XO.

Another example is they use action one to do something negative (bad OPG, Scout, etc.), second action - reveal ( power goes off, discard to 3, super crisis etc). Then they have a turn as a revealed Cylon.

On round one or two this more of a concern to me, but eventually, you have to XO whoever is best… pilot for raider danger, someone for repair, president for Quorum… etc.

Oh paranoia, probably the reason I love this game!