This question is answered by the IRS: https://www.irs.gov/affordable-care-act/employers/questions-and-answers-on-employer-shared-responsibility-provisions-under-the-affordable-care-act
No. Whether an employer member of an association that offers coverage through an AHP is an ALE that is subject to the employer shared responsibility provisions depends on the number of full-time employees (and full-time equivalent employees) the member employer employed in the prior calendar year and is unrelated to whether the employer offers coverage through an AHP. An employer that is not an ALE under the employer shared responsibility provisions does not become an ALE due to participation in an AHP, and an employer that is an ALE under the employer shared responsibility provisions continues to be an ALE subject to the employer shared responsibility provisions regardless of its participation in an AHP. (The only circumstances in which multiple employers are treated as a single employer for purposes of determining whether the employer is an ALE is if the employers have a certain level of common or related ownership. For more information see the questions about common or related ownership in this section.)
For more information on AHPs, see regulations issued on June 21, 2018 by the Department of Labor.