It's time for my annual etiquette lesson to the Christmas Warriors. If someone wishes you Happy Holidays, you're supposed to smile and reciprocate, not be a giant douche and berate them for not saying exactly what you think they should have said.
At this moment, and until something like December 24th, it doesn't make sense to wish anyone "Merry Christmas" unless you are deliberately trying to be niggardly with your blessing. After all, there's the whole holiday of Advent in which to be merry and Christmas Eve and then Boxing Day and Epiphany and New Years. So saying Merry Christmas is akin to saying "enjoy December 25th but none of the days leading up to it and none of the following days".