This isn't ludicrous at all. We don't understand the Scourge or how it works so why couldn't it be re-engineered to do something else or used in a manner other than originally intended?
I think mouthwash was originally marketed as a household cleaner or something like that (Listerene), there's toxins used to treat migraines and tighten our faces, and radiation is used to fight certain diseases.
So why couldn't the Scourge (which seems to counter energies of one nature) be used to counter the effects of eezo exposure? Very plausible in my opinion.