The absence of something
Well, no, it's not irrational at all. If I know a fundamentalist Christian is likely to scream at me at the merest hint of dissent, it's rational for me to avoid that conversation. I don't like being screamed at. It's also not irrational for me to tiptoe around an abusive husband and try my best to avoid angering him.
But neither Amanda nor Richard D are saying that it's irrational, are they? They're saying that it's unfair that the double standard exists, that it would be desirable if it didn't, and that the standard arguably perpetuates actual harms by enabling a sense of entitlement amongst (a subset of) the religion-having.
To my reading, the "it may be irrational" comment referred to the fact that Amanda has some respect for the non-cry-religious by contrast. If I'm wrong, Amanda, let me know.
On another note, atheist cards? The hell? To celebrate what occasion, exactly? "Happy Tuesday"?