Closing the loop on this.
I was unsuccessful drilling out the broken bolt. Read: without a lift, it was a pain in the ***, so I punted and took it to an independant shop. They drilled it out and moved up to the next larger bolt size and tapped it for that so I'm good to go.
As a backup, I snagged a complete swing arm from feabay, for $50 plus shipping (so about $80 bucks). It was cheap insurance. The shop charged me a whopping $99 to fix it. So I'm good to go, and have a spare swing arm for an 06-09 if anyone else finds themselves in the same boat.
Happy to pass it along.
-=MD