He'd be wrong to blame Bush for the entirety of the growing debt, but he's not wrong that some of it does fall at the feet of the previous administration. All those shitty laws and deregulations that caused the economic meltdown don't just go away overnight, so the effects of those that remain can still be partly blamed on the previous administration. However, the lion's share of the blame falls on the both sides of Congress, both the obstructionist Republicans and the worthless Democrats who just whine about the opposition being obstructionists rather than trying to work with or around them. They're both just sitting there saying "nope, won't work with the other side, fuck 'em," so nothing gets done due to the split Congress. Thus, this one falls under the "bullshit two-party politics" label as well, which shouldn't come as a surprise to anyone.