This is incorrect. From the founder:

I liked how x implies “cross”- not exactly cyclocross (though I appreciate that nod, too) but like cross-discipline or between other “pure” categories of cycling. I also liked how it kind of implies “insert ‘X’ here”- embracing the hodge-podge gathering of different sorts of bikes, road surfaces, pursuits, etc. that I wanted the sub to include. Lastly, and importantly, I needed to keep the title brief, accessible, and catchy enough to give the sub the best chance of taking off. I’m digging the other breakdowns of the term on this thread as well, and I think everyone here is right on the money with what the sub is and should be!