He lives there and can cherry-pick it. Also I'll bet the usual range of Jackson conditions in March trains him for some of the nasty backcountry stuff he skis in the summer to keep his streak (should be over 100 months by now ) alive.I haven't experienced Jackson in March, but I believe that Bob Peters from Epic isn't that negative about it.
I'll admit humility. I'm a tourist, not a local, and try to find decent conditions on my trips. Since Patrick's ski ability can pass for a local, it probably matters less to him, except when lifts are actually shut down (thus the tree line comments). Given Bariloche's admitted base area snowfall of only 60 inches, I suspect decent off-piste tree skiing there is rare.
I think Patrick is right about this. Fortunately these are the places skiing is most likely to be good if it hasn't snowed in a couple of weeks.the only real places where advance commitment is really required is Portillo or LL.
The lower altitude places farther south are best visited midwinter, just like their Cascade and Kootenay counterparts. Of course the world-class tree skiing is the big allure of the latter, so the South American areas (even those like Chillan and Pucon with fairly abundant snow) are more speculative due to storm shutdowns.