To the best of my knowledge (and IANAL...), Match has no standing in this regard, and therefore is in no position to be making any demands. Match is not the FTC (or Canadian equivalent).
I'm no lawyer, either (nor am I ANAL), but I think you're correct. In addition, I believe the FTC only really has jurisdiction to intervene here if it believes actual consumers are being harmed by plentyoffish making the claims they are. Since it's a free site, it seems unlikely anyone's being harmed by anything plentyoffish is doing, except possibly for some wasted time. And, in this respect, I'm sure plentyoffish is no worse than a lot of other time-waster web sites.