He almost certainly doesn’t. The emergency declaration law does give Abbot shockingly broad authority to “suspend” any regulatory statute or rule that interferes with disaster relief efforts. So his previous EO banning local mask mandates could at least purport to be based on his reading of the law as giving him the power to suspend local emergency measures (Such as mask mandates by public schools). It’s not clear
at all where he thinks he gets the authority to tell a private business that they can’t set their own rules about vaccines.