Well that's the thing... It does have one big bulge on the sidewall where some of the threads have failed. My new tire should be here in a few days, but until then if I can't resist riding the bike I might try booting it.
Going easy on the bike isn't an option either. I built it up to withstand a lot of pounding (36x3 wheels, etc) and I intend to ride it that way. It's too fun not to!
I do ride plenty of old tires without issue. The tires on my SS road bike are from 1984 and they're just perfect.