Official JW.org doctrine: Apostasy is abandoning, deserting or rejecting Jehovah’s organization [the Watchtower Bible and Tract Society]; so by definition, anyone that 'abandoned' (or has let themselves become "inactive") is an apostate.
Contrast this with the regularly accepted definition of Apostasy: Apostasy in Christianity is the rejection of Christianity by someone who formerly was a Christian.
So you can be an apostate in the JW simply by abandoning the WTBTS organization (becoming inactive), whereas in most churches you must reject the entire Christian faith (so you can change churches, denominations etc) to be considered an apostate.
My experience:
I have been officially inactive for a decade, I am officially also still an MS, I am also labeled an apostate by many. Mostly because they tried to but failed to disfellowship me, but I was able to hold any change in status with legal action and they've since forgotten about me. I'm sure someone at some point will simply throw out my publisher card.
The apostate label does not follow any status in the JW organization, it is something you can be labeled whenever you disagree with the ever-changing WTBTS official doctrine. By definition, anyone inactive is disagreeing with the WTBTS doctrine that you have to attend meetings to be "saved", so yes, inactive ones are apostates.
If you post here, as many a faithful JW do, you are considered an apostate.