True, but in this specific case, you only need to find a taxable investment that returns more than 5.49% to come out ahead, and if you are in a tax-free account, like a Roth, it only needs to return 4.11%. You can absolutely do that with a guaranteed return. A money market account or bond would beat that.
You can't put $489 a month in a Roth IRA.
A Roth isn't tax-free, it is tax deferred.
It is hard to compare apples to apples when taxes and risk aren't factored in.