I dont know if i would use "unstoppable" based on the price trend so far :-) But i agree with the broader picture. The stock has taken a massive hit for the departure of the old CFO a while ago now and has simply not recovered to the same position (near $20).
At the same time (last 2 weeks), Fireeye and PANW have made sizable stock moves.
Given the cash and market position of FTNT I think this is a safe medium term play. Downside is very limited (almost a billion in cash alone). Upside can be a nice 50% from here.