Stock price when the opinion was issued
Pay attention to the old highs (~$200), and stock's getting close to them. Recent peak does appear to be breaking the last one. Probably will get to the $200 area, so still a few bucks to go. From there, that's when to start chewing your nails, as it's stalled there before when those old buyers just want their money back.
A tough one. Lots of speculation in the name. If you look at it with a purely quantitative view, you'd be a bit nervous. Still in the high growth, ramping up operations, risky "startup" phase. Improving ROC. Valuation makes him pause.
Doesn't have a problem owning it, but should not be core. If your portfolio has 20 stocks, 5% each, then this one should only be ~2%. With today's earnings pop, good to trim.
He trimmed a bit. He'd beef up the position again if it dropped 10-15%. One of the companies that will dominate the world for the next 1-2 decades.