If you want to be so general, then anything can be considered mathematics, at which point it kind of loses its meaning. For me, mathematics is any system of symbolic manipulation built on top of axiomatic set theory, ideally having some algebraic structure. Given that the universe is comprised of things and not symbolic representations (unless you want to get really general about what a symbol is) that seems to disqualify it right there. Can we approximately describe the universe using mathematics? At the gross level, with the inclusion of fuzzy sets/probability theory, sure. At the fine level, I'm not so sure we can accurately represent the universe using less information than the universe itself contains - thus you aren't abstracting anything.

I mentioned the incompleteness theorems because they suggest a universe that was a consistent logical system would be arbitrarily constrained from valid portions of its state space - a testable hypothesis with no evidence. Of course, if you toss out consistency then all bets are off.