The Cal Poly brand is highly regarded so this should increase the prestige of Humboldt with those who are not already familiar with the school.
CP-SLO EE grad here. Prestige needs to be earned based on the quality of the graduates which depends on the faculty, curriculum, and resources. You don’t get it simply by sharing a name. I do wish them success with this change. At least they’ll have a couple of successful models on which to base themselves.
I learned at Humboldt university of Berlin, never knew they had one of the same name in California! You never can tell, with universities...