The wording of the Executive Order says he wants to deport legal immigrants on welfare. He doesn't need an excuse to deport illegal immigrants if we catch them.
To prevent illegal alien welfare fraud it is as you noted necessary to catch them
The federal benefits dispersed by a plastic card must be administered by a federal rather than a state employee to a person having proof of citizenship, a birth certificate. I don’t see how it can be made to work because in Sanctuaries, any piece of paper including a blank paper will be accepted.
Until the sanctuaries are removed, there is no solution. Whining about kids must not win the day. Kids must be deported or families separated.
It is also aimed at legal immigrants. A vast majority of legal immigrants end up on social welfare benefits.