Actullay that idea was shot down previously. It was one of the suggestions a few years ago. The issue is that bonds are a loan. The City (and/or County) would guarantee payment to the investors. Muni bonds, at certain market times, are attractive to investors. The interest they earn is not taxable income.
But the City has to have a means to repay the borrowed principal and the interest owing to the investors. It could be with sales tax, hotel tax, food and beverage tax, but it has to come from somewhere. The rent generated from the lease of the arena is likely not enough.
If this falls thru, they may try this again, but it may not be any more popular.