It's all about context and intent. In the context there is no intent to apply or relate the term retardo to anyone suffering from a mental handicap.

Except that I haven't made that claim, and that's not my point anyway. I'm questioning the suitability of "retardo" as a rebuke term in this context because it equates mere ignorance or stupidity with a condition (mental disability) that for most of its sufferers, is not reversible.