50k limit was put in because researchers couldn't get fossils that were carbon-14 free

it's because after the 50k mark you've got so little c14 that you couldn't use it to date samples that old with the methods at the time that limit was established. If you tested anything older you'd still get 50,000 years because we didn't have the tools to tell the difference between a 50,000 year old sample and a 60,000 year old sample at that point.

That problem was well pointed out at Talk Origins.

Can you post the talk origins page you're refering to? The closest I could find to what you're claiming has them finding fossil fuels with no detectable c14 as well as some that had a lot due to contamination from surrounding rock.