You do realize that the CRJ is certified up to FL410, and thus they were not pushing the aircraft passed anything, or doing anything that the airplane is not capable of doing.
Of course, the CRJ is not the best aircraft for high altitude work, and will struggle to get above 350, or even 330, when loaded with passengers and cargo. However, on a ferry flight, when light there
Sure, in an aircraft like the CRJ, stall speed will be closer to the cruise of Mach .74 in a CRJ when up at Fl410, but not inordinately so.
Was there a mistake on the part of the pilots? Possibly, even, i would say, probably. Were they doing something that the aircraft can not do? No.
Isaac