Marx position was not about who shall be emancipated or not but who have an interest to struggle for the revolution. In his mind, a part of the proletariat was too precarious, and could be easily corrupt by the bourgeoisie. Such as thieves and cops.
However with the development of the communists party and their propaganda around ouvrierism, the pride of workers turn to be the pride to work. The lumpen became a slur against people that do not work enough; a conception close to the far-right view of unemployed "parasites". That's why nobody use that term anymore, even if it's still accurate for cops and managers