It could be a mistranslation and just refer to DTS/CTCSS. The cpu isn't powerful enough to implement real AES encryption and the datasheet doesn't mention a hardware crypto module. It could be an inversion scrambler, that's not difficult to implement in software and even if it doesn't have that stock someone could implement it. But scramblers have limited utility now. They are really only useful to annoy others, they are trivial to defeat. Undocumented encryption capabilities are also not unheard of with Chinese made ham radios either. Seems the FCC really only cares when people make a menace of themselves and draw their attention.