I'm not sure what that has to do with drug testing. If you wanted to require net beneficiaries to have their finances audited, I suppose I could understand that. They're receiving more money than they pay back, so you want to make sure they're not hiding something. But what does drug testing have to do with it?
I assume it's clear to you that the proposed bill has zero chance of becoming law, and the congresswoman who proposed it didn't do so because she really wanted it to pass? She proposed it to draw attention to our hypocrisy in the different ways we treat rich and poor people. Because, as she said, she is "sick and tired of the criminalization of poverty." What we give to poor people is peanuts on the scale of the whole budget, but we make them beg and humiliate themselves to get it. So she suggested making rich people humiliate themselves in the same way, to make us all think a bit more about what we're doing and why.
I don't actually support drug testing of rich people. I doubt she does either. But as a way to illustrate what a bigoted society we have, I think her proposal is great.