Agreed, it's just the vocal-minority of Hoiberg fan boys that make it annoying.
I don't get the personal animosity, but I also don't get trying to shame people into wishing success either. If Fred is moderately successful at Neb - say make the tourney every couple of years, maybe win a tourney game or two every few years, there's a good chance that has a little impact on ISU. Even then he may be able to bolt to the NBA again, certainly if he's wildly successful.
My view is that I want ISU bball to win, period. Fred being successful at NU probably has some negative impact on ISU, as would Minnesota or Mizzou. The impact is less than that of another Big12 team, and less than that of Iowa. For that reason I'd prefer he lose there. Nothing personal, but NU sucking is better for ISU.
As for the "Fred's done more than anyone for ISU" strategy in shaming people that are bitter, I'd say first, Fred got a good power conference job when he was not sniffing a mid-major or probably even low major job. He got the raises when he wanted them, there was no hometown discount. It was a great, mutually beneficial transaction. Fred doesn't owe ISU anything and ISU doesn't owe Fred anything. Both came out really well in that relationship.
Second, while of course Fred has done more for ISU than some individual fan, but I think that's a dumb argument. If we take the aggregate of the tens of thousands of fans that don't like the prospect of him winning at NU and it's potential impact on ISU, and look at their donations, ticket sales, merchandise purchases, tuition often over decades and multiple generations, I'd say that aggregate of fans that represent ISU in this situation, have done more for ISU than Fred. So if they want to be pissed about it, that's their business. Fred feeling like NU is the best fit for him and his family given other opportunities available (maybe there weren't other great options available?) that's his business.