I broke my topwater rod. I was thinking of using my spinnerbait rod for buzz baits. Would there be any draw backs to this? Thanks!

I can't see any. Realistically, spinnerbaits and buzzbaits call for either similar or the same taper depending on your preferences.

x2 on what Adam said, no reason not to throw them on the same rod.

Have you thought about your rod?  You are asking it to perform in a different function that you asked of it previously.  Oftentimes, people freak out when this happens to them.   Fishing rods are just like people, except they don't audibly talk, or breathe or stuff like that.   I'd be concerned about the mental health of your rod, if you are consistently asking it to switch duties.