No kidding? I've never heard this before.
Now, I have heard that a comet fragment may have caused the Thera eruption in 1628BC.
Actually the theory is you get a hotspot and flood basalt on the OPPOSITE side of the planet from the asteroid impact, through focusing of seismic energy.
It's been out there for a while, and the people behind it aren't kooks, but it's not widely accepted. There are some interesting "line ups" of large impacts with hotspots on the other side of the world.
One fly in the ointment is that it's now pretty clear that hotspots aren't perfectly stationary in the mantle with the plates moving over them; the hotspots themselves move some.
Actually the idea of impacts causing a hotspot on the opposite side of the earth has been around a long time...
This is a PDF paper from Sandia National Labs about it in 1994..
http://www.osti.gov/energycitations/servlets/purl/10197028-5vKwmj/webviewable/10197028.pdf