That's why it's important that it's a one-time donation, not a recurring additional paycheck. If you give 'the poor' an additional paycheck, yes, it will have an impact on the willingness to work and save. If you give them a one-time donation, on the other hand, they can use it to improve their lives in the longer term, without reducing work. That's what the data (as quoted in the article) shows.

I believe the reasoning for why that should be goes back to the cycle of poverty (http://en.wikipedia.org/wiki/Cycle_of_poverty). It's harder to make more money if you don't already have more money. By giving a one-time lump sum, you give people the opportunity to dig themselves out of that hole. Eating better, dressing better, buying things that last longer, these all have big impacts on how much one can save and earn. Even getting some basic education helps enormous amounts. In the end, it might even lead to people being more willing to work harder and actively save more money.