The article wraps up with "The results are not conclusive, given the various uncertainties involved. For example, it's difficult to date supernovas precisely; the inferred timing of the Vela explosion may be off by as much as 1,500 years, Brakenridge said. But he thinks that the new results, which were published online last week in the International Journal of Astrobiology, show that more research into a supernova-radiocarbon link is warranted.
“What keeps me going is when I look at the terrestrial record and I say, 'My God, the predicted and modeled effects do appear to be there," Brakenridge said.
He's not the only scientist to suggest that supernovas may have significantly affected life on Earth. Other studies have postulated that nearby star explosions have caused or contributed to some mass extinctions, by altering our planet's atmosphere and causing climatic shifts."
My observation. The c-14 dating method may or may not be impacted by supernovae too.