Thanks for the replies, everybody.
Since it's a throw-away program he can just keep it closed source and not put it on GitHub and move on to his next game.
I'd like to put it on github because one.) I figure being able to use github would be a useful skill and 2.) It would make it easier to get feedback on my code.
Also, my next game will probably need a timer also, so I might as well change the code now. The problem I'm having is that I don't know what I could change. I could get rid of some member functions, change names, etc. I looked up other implementations for a Timer class, but they were mostly just slight variations of the one I have now. Any suggestions? (I'm not trying to ask you to change the code for me, I just want ideas for what I could change).