He did no such thing. He proved undecidable problems exist in any system powerful enough to be useful. That doesn’t make those systems useless, though.
The trouble is the creators of OWL wanted to have performance and reliability bounds. That is, they want to make systems that act like more like a conventional database server than an SMT solver.
I think they could have made a more expressive standard and something like that might have had more appeal to people but been less consistent in terms of performance.
He did no such thing. He proved undecidable problems exist in any system powerful enough to be useful. That doesn’t make those systems useless, though.