Rationality, but only to the point of expediency

Another example here, I suspect, of my wasting my figurative breath, but 'nothing ventured....'.
I read a post on a blog earlier on, a blog whose author I agree with on a goodly number of issues, a person who presents himself as atheist, rational and sceptical, all traits likely to commend him to me. The post was arguing against yet another attempted justification by the religious right for their opposition to marriage equality. Amongst the recycled nonsense from the hater was the ridiculous non sequitur about gay marriage leading inevitably to toleration of polygamy, marriage of people and animals or inanimate objects....and the inability to justify 'discriminating' (the hater's word) against paedophiles. The blogger had little difficulty in elucidating the stupidity of the hater's 'arguments', but, of course, when it came to the final point, the armour of rationality (not so) mysteriously vanished. The difference, the blogger argued, between 'paedophilia' and homosexuality between consenting adults, was that 'paedophilia harms someone against their will, before they are of an age to make a rational choice', whereas consensual homosexuality 'obviously' doesn't. Of course, being a 'rationalist' blog, you would expect some evidence for such a claim, some definition of terms like 'harm', 'against their will', 'age to make a rational choice', even 'paedophile', wouldn't you? Well, you'd expect in vain, I'm afraid. Just the bald statement of the 'fact', no definition of anything. If the word 'paedophile' was being used according to its correct definition, describing the attraction of adults to prepubescent children, I would probably be inclined to agree with the 'age to make a rational choice' assertion, at least, but in the total absence of evidence that the word was being used in that way, I'm afraid I have to reserve judgment. What does seem evident to me, however, is the readiness of even those who are otherwise rational and dedicated to fairness and equality to throw the likes of me 'under the bus' to make their point. And just to put the icing on the proverbial cake, I saw, on a different post, that (literal, in this instance) juxtaposition of 'paedophile' and 'rapist', again. What was it Goebbels said about 'The Big Lie'?

Love & best wishes to all
Sammy B