It's not arrogance. Explain how Walton has any more credibility by virtue of playing at UCLA (all american means nothing) than any other alum of that school or of any B1G school. Playing alone, without an honest, in fairness, objective look at why UCLA made this decision is just an uninformed emotional opinion based on how Walton feels about it.
His opinion was, and is, pretty meaningless when the not so secret objective of big time collegiate athletics is money. And success (because, believe it or not, a lot of university endowments have received funding from those folks who like to see the university's sports teams win. Money helps winning. Great Facilities helps winning. Money helps build great facilities. Money helps recruiting budgets. Significant recruiting budgets helps winning. Walton either doesn't recognize this need for more revenue or is afraid of UCLA losing, the latter of which I doubt because, you know "champions" which makes his opinion based in fear or ignorance.
Maybe what Walton is afraid of is UCLA won't be able to stand up to the greater competition in football and, more specifically, in basketball and becomes an also ran sort of irrelevant school in the B1G.
USC, on the other hand, would like to see more games with OSU, MIchigan, Penn State, Wisconsin, etc. These seem like better matchups than Colorado, Utah, ASU, AZ, OSU, WSU etc. Even Iowa, Minn, MSU would be good matchups. USC still wants to become national champions in football and see the B1G as a better stage to do that from.