Please keep us informed of progress? I will be getting around to keeping yeast starters in the fridge eventually. I would really be freaked out if the starter smelt off, with a fermenter full of goodies just waiting for yeast to be added.
The DMS is a telltale for a bacterial infection, so the questions are
1) level of DMS?
2) are the bacteria still viable?
If the bacteria are no longer living, then let's assume you can smell DMS in 100ml of starter. If the starter is diluted 200:1 by putting it into a 20l brew, is the DMS still detectable? The brew may be a goer.
As a friend once told me, 'dilution is the solution to pollution'.
If the bacteria are still living, then I guess you will throw it out after a few days. Let us know?