Patents can be found invalid for many reasons.
I remember a case where a guy had patented swiveling handgrips for a wheelbarrow. Somehow the patent ended up inadvertantly giving him a patent on the whole wheelbarrow. It was struck down in a court case, and he lost his patent. I'm not sure if he was ever able to resubmit for a new patent for just the handgrips. It's not a quick or cheap process.
His patent may not be quite as "Locked up" as you think.
Besides, a patent merely gives you standing to sue. It's still up to you to defend your own patent at your own expense. You can't just call the cops and make a complaint. If you lack the financial means to initiate and fight lawsuits, your patent won't do you ANY good.
I'll bet Ryobi or Dewalt have a lot more resources than this guy. One of them might decide to produce a saw with the same feature done differently, and go in understanding he might sue them. The little guy occasionally wins those sorts of battles, but it's rare.