I'm a Jack keller fan, so it surprises me that he'd suggest aging in plastic. I wouldn't do it- I don't even age wine in my better bottles. I'd bottle and then age before I'd age in plastic water bottles. To me, there's just too much risk of oxidation in those plastic containers, and after all that time and effort I'm not willing to chance it. I bulk age in glass carboys, and if I need the carboy, I bottle the wine and age it. If the wine is clear and stabilized, and not throwing lees any more, it's ok to bottle.