FR: ne vaut pas aveu de dopage - absence d'article

[SydneyBox]

Greetings.
Is there a grammatical reason why there is no indefinite article before «aveu de dopage» in the following sentence) about Lance Armstrong from Le Monde (sport)?
«Après cette décision, qui d'après lui ne vaut pas aveu de dopage mais symbolise son refus de la "chasse aux sorcières" de l'Usada, le gendarme de l'antidopage»

I would translate «qui ne vaut pas aveu de dopage» as “which does not constitute an admission of doping” but I would expect «un aveu de dopage»

Thanks in advance

 

[jann]

I may be mistaken, but I don't think the reason is grammatical, and I believe the sentence would be grammatically correct if you included the indefinite article.

Instead, I think it's just a matter of idiomatic usage in a legal formula. Here's another example (where you would probably have expected to see the definite article): Cet enregistrement ne vaut pas agrément de l’Etat.