the economy tanked because of the last administration, that's not relevant...

If one can read and understand the Englist language, Biden obviously did not 'dismiss' the contention that "decisions made under George W. Bush [are] one of the main reasons why today's economy is in such turmoil".

Translation for the cognitively impaired, Sawz: the public rightly continues to blame Bush for tanking the economy; and second, this may be mostly irrelevant in 2012.

Not 'relevant' now, perhaps (in the context of what the Veep was discussing), but none the less still TRUE