It depends on the plastic!
I always primary in an "ale pail"- that's usually about 3-5 days or so. It's fine, and it makes it easy to stir and remove fruit, etc. Then, I rack to glass and keep it in glass until it's bottled. I bought some Better Bottles, and they can be used for wine, but I use them mostly for beer or short term storage. If I know I'll be racking a wine very soon, I'll use the BB for secondary. My reading has always shown that the BBs are fine for wines, but it just doesn't seem "right" to me to leave it in plastic for long periods of time, like for bulk aging.
This isn't based on any kind of fact at all- just what feels right to me. I don't know if "never let your wine touch plastic" is based on any kind of scientific basis- what does he use for racking canes/airlocks/tubing? I mean, you could get a stainless steel racking cane, I guess, and vinyl/silicone tubing, but I even use a big plastic spoon for stirring so I can't imagine going completely plastic-less.