To me, an Expat is a higher position foreign executive coming here to work usually MNC. Once his/her work is done, recalled or he resigns from the company that sent him, he/she has to leave the country unless they choose to stay here at which time their status is now an Immigrant applying now to stay here permanently as PR and eventually a citizen... especially those who found a mate here.
I call lower level workers as foreign workers or foreign talent but that again is NOT immigrant but status to work here but will leave the moment that status changes or cancelled.
An immigrant is someone who comes to live permanently in a foreign country. regardless coming here with a job in tow or not.
that article seem to be more politicizing the narrative more then it keep to the accurate use of the words especially in our local contexts I feel.
I know of Singaporean who work overseas on expat status