That's probably because you don't understand how the U.S. presidential election process works.
One of the clear mandates in the constitution for the selection of a President is that the Presidential Electors must all convene on the same day in their respective state capitals to cast their votes. For the 2020 election, this day was established as December 14th.
At that time in 2016 there were still several legal challenges in place related to the November "popular election." The purpose of having a set of alternate electors seated was to prepare for the real (through perhaps not likely) possibility that one or more of those challenges would be successful. Without having those "alternate electors" cast their votes on the appointed day in December and sign those sworn certifications as Trump electors, the end result of a successful legal challenge in Michigan would have been as follows:
1. Trump wins the challenge on the merits of the case.
2. The state’s electoral votes are given to Biden anyway because the Biden electors were the only ones who met and cast their votes on the appointed date (December 14th).
Re: 22 - they were not declaring themselves as alternate electors. They were representing themselves as lawfully selected electors. They were not, as they were not the electors designated as a result of the Michigan State Board of Canvassers certification of the election.
Read 19 of the complaint. They asserted they were the duly elected and qualified electors for the State of Michigan. They were not.
Apparently the AG does not understand how the electoral system works either.