bert,
No, it does not say directly that you can't.
Make no mistake here ---> just because it's written that you can't, does not per default mean that you can :)
If you base your qualification on a weld which is part of the production, you will be a bit limited on qualification range in terms of positions.
Since you already has invited the tpi to witness the production weld, why not do a correct test?
As I mentioned before, some welding processes requires mechanical tests in addition to RT/UT
3.2