That's fine for them but their ignorance (again, no aspersions!) doesn't change a thing.
The truly ignorant are those who choose to be offended on another's behalf, especially when it's over a colloquialism that has a different meaning in the context used, or where no offence was intended.
If I intend to offend you, your family or your friends (or culture), you yourself may be offended. If I do not intend to offend you, you have no right nor reason to be offended - even if it seems I intended to offend someone else. I get so sick of ignorant arrogant scum who think they have a right to be offended on other's behalf. Keep your self-righteous mitts OFF and get your nose out of my life. (not aimed at decoherence unless you fit the description :) )