There's a funny piece of revionism about the appointment being done for Ducey to win in 2022 but that ignores the fact that if he wanted a placeholder he could have appointed someone from his staff or some hack from the local party. He then easily could have either ran in the 2020 special election or in 2024 against Sinema.
Besides it wasn't assumed that McSally would lose this race; Kelly wasn't known to be running when she was appointed & although she ran a poor campaign it wasn't this awful. If he really wanted someone to lose the seat he could have appointed someone much worse like Ward
McSally was appointed because she was seen as the strongest choice & because they hoped she could use her Senate seat to save this race in 2020.
This. In fact they already had a place holder, Kyle