I have never seen it proven that +Thuc said he withheld his intention at Palmar, just a repetition of this allegation in various anti-Thuc articles.
In fact, in 1981, he issued the following declaration in a German magazine (though it's not a great translation):
I testify to have done the ordinations of Palmar in complete lucidity. I don't have anymore relations with Palmar after their chief nominated himself pope. I disapprove of all that they are doing. The declaration of Paul VI has been made without me; I heard of it only afterwards. Given the 19.XII.1981 at Toulon in complete possession of all my faculties.
As far as his withholding of intention for the NOM, he didn't exactly say that either. He said that he didn't really con-celebrate because he did not receive Communion and that it's not a Mass (on the priest's part) if he does not receive Communion.