NYT 'stylebook' says, "rather than the sinister sounding 'illegal alien'". So, they are not allowed to use the actual legal term that describes the status of illegal aliens?

At least they correctly prohibit the use of the euphemism "undcoumented", but how are they not aware that "illegal immigrant", their preferred usage, is itself a euphemism for correct legal term "illegal alien"?

Federal Law is crystal clear on this point. The NY Times simply refuses to use the proper legal term - and requires all of its reporters to comply.