Under the "Body of work" premise that determines seeding Gonzaga clearly deserves a #1. 6-0 vs top 25, only 1 of which was at home. Even if we want to say St Mary's is really just an 8/9 type team, they went 3-0 on neutral courts against 3 teams that will be seeded between 2 and 4 today (Florida, Iowa St, Arizona). They did everything that was asked of them. The power rankings validate them. This was not a team getting a #1 seed based on beating up 34 sisters of the poor - just 21. They played 13 top 100 games, 6 top 25 games. and that is enough to make a resume assessment.
So they have a strong enough resume for a #1. But the question of always is whether their weak back end fails to make them as strong as other teams and really a top 4 team. by the time the tourney starts But the criteria is entire body of work, so on that front they do deserve the #1.