So then why isn't the mudskipper a "found" link? Doesn't it appear to be some sort of transition between a fish and amphibian or land reptile?
No. The mudskipper does NOT so appear. It has fins, not feet. It has none of the amphibian skull anatomy of Tiktaalik or other genuine transitional candidates. Etc. And of course as a living creature, with no indication of a long fossil history, the mudskipper is not properly positioned in time to be a transitional, even ignoring its anatomical unsuitability.