Radiometric dating on the Traps has tightened down to about 7 million years, but if anything, the P-T extinction and the traps had a common causative event -- obviously an impact. It's not unlikely that the most likely candidate for the impact site *is* the Siberian Traps, which slowly covered over the astrobleme.
One of the arguments I've heard for the P-T extinction not being caused by an impact is the lack of an iridium layer, similar to the one found for the Cretaceous extinction. I've also heard that the Permian extinctions appear to have occurred over a long period of time, rather than being a swift die-off.
“...astrobleme...”
Darn. I thought I had a new word to call liberals...but then I looked it up and found out it’s just a geological term.