"OK. But it isn't marijuana "itself" that does this. It is one or more chemical components that we can isolate, right?"Correct. The study tested two cannabinoids isolated from marijuana, not whole-bud marijuana.
"But just because these components are present in marijuana I can almost bet that it will be reduced to an argument in the fight for legalization of smoking weed."
Well, yes, it's going to go there eventually. Pretty much all conversations about the medical efficaciousness of marijuana (or marijuana-derived compounds) bump up against the legalization topic. This is because conducting research on a substance currently deemed illegal by the federal government is very difficult. It's also because the government labels marijuana not just illegal, but a drug "...with no currently accepted medical use and a high potential for abuse." (This is the 'Schedule I' classification).
Marijuana's classification in Schedule I, a category for "the most dangerous drugs of all the drug schedules with potentially severe psychological or physical dependence," is ridiculous. For what it's worth, here are some drugs legally considered less dangerous, or psychologically and physically dependence-forming than marijuana: cocaine, opium, methamphetamine, oxycodone, morphine, codeine, fentanyl, Dexedrine, Adderall, Ritalin, Vicodin, Valium, Ambien, ketamine, and anabolic steroids.
"I'm not saying it shouldn't be legalized (perhaps it should, perhaps it shouldn't), but that it's an entirely different question."
Absolutely. Marijuana's legalization as a consumer item has little to no bearing on this finding, or vice versa. That said, its current medical status is in debate, and whenever a potential medical usage comes up, that topic is going to come up with it.