I don't think so, I think it more means it would fall more in line with other observations, whereas other (currently just as plausible) theories would mean we s

I don't think so, I think it more means it would fall more in line with other observations, whereas other (currently just as plausible) theories would mean we saw something very new. The "comet" theory, for example, suffers from the fact that while we observed acceleration from the object, we haven't yet found evidence that there was any gas or matter being expelled from it that would cause the acceleration, which you'd usually see with a comet. It would be less surprising for someone to come out tomorrow and say they found evidence of matter being expelled from the object, suggesting it's a comet, than someone proving it was a solar sail, but that doesn't make it more likely based on the evidence itself (and not our preconceived notions of how common certain stellar objects are based on our very tiny observational window).