Why did it take five, or so, years to discover immigration as a problem? I think the administration is in legacy panic mode.
It's because they can hear the outrage and they can see the danger up ahead with the mid-term elections.
Bush is pro business so he will do what he can to support them in their efforts to source affordable labor. Secondly, he is a fairly compassionate man and I don't see him as being willing to round up people in the middle of the night and throw them out. To him that is simply wrong.