What have you needed out of ANSI SQL that is a gap in its Turing Completeness? Totally serious. A great many things can be dismissed as not being Turing Complete, so please provide us with some examples of why this is bad in ANSI SQL.
My interpretation of the parent post was that it was a response to a comment about vendor lock in. I was only trying to point out that it is not always possible to ensure compatibility between databases by writing strict ANSI SQL.