Proving a negative is devilishly difficult. That is why the burden of proof is on the one making the claim. State a reliable source verifying the claim that there is no mention whatever of ACT in any protocol or recommendation of any of the organizations mentioned. Moreover, cite a source verifying the claim that "mention" of a group in a protocol or recommendation constitutes recognition or acceptance by these  organizations. Cite a source even to verify the claim that any of the groups mentioned "recognize" or "accept" advocacy groups as a matter of policy. Most especially, cite a reliable source that "recognition" by these groups is a requirement to be a part of the "mainstream" of the "mental health professional community" (or even what that community is). Most especially, cite a reliable source for the claim that ACT's "advice is not sought by these groups, nor intended to be so" by the organizations mentioned.

Without verifiability of the statements made, the entire section must go, and I am prepared to delete it. It can be reinstated when verification is found.