It's hard to imagine a serious practitioner or researcher not considering all the available data, but I'm sure it's also true that there are biases on the part of everyone. I'm sorry you didn't find my explanations more helpful, but I guess I shouldn't be too surprised. I'm sure you didn't make your own comments in a vacuum!
For what it's worth, I would just say that since prostate cancer can progress at quite varying rates, the risk of it spreading beyond the prostate is better calculated by the aggressiveness of the cells than the current progress within the prostate. Since removing the prostate remains a standard of care, even in the presence of alternatives, the size of the nodule is perhaps not as important as how many parts of the prostate have nodules, how aggressive the cells producing the nodule(s) are, and so forth. I am of course not saying that volume of cancer doesn't matter, but just that it is perhaps not as good a guide, especially alone, for the wide range of prostate cancers that are lumped together as "prostate cancer." Also, if the volumes are actually quite low, like 1-5% as opposed to 10-50%, absolute size, again, may be not the best factor in determining time to metastasis (when the cancer leaves the prostate and begins to spread through the body and into the bones.)