Initiate a clock counter that in PVE Ques auto-kicks a player after 5 to 7 minutes of inactivity. Can restrict it to public ques to make it "less" of a server load issue and some people may initiate private ques to run alternate accounts or afk friends through.
None of these things will work. What you are seeing is not people who are AFK, but people who have consciously chosen to exert the minimum possible effort to receive their reward.
The reason this happens is because of the Leaver Penalty. Without this enforced lock-in, people would just ditch these cretins and requeue without them. It's precisely because these guys have a captive audience that they are regarded as such a problem, despite their relative rarity.
The truth is there is not actually an epidemic of these people. I PUG ISE regularly, have encountered maybe 1 or 2 since I first started. I have full sets dating from S6, and over a dozen T5 Omega Rep toons, so it's reasonable to say I STF reasonably often. Encountering 1 or 2 actual leechers is not exactly an event I would consider to be so frequent as to warrant thread after thread of this, but clearly, this has a deep emotional impact on people.
all I can say is u been lucky I play a lot of stf / pve missions in the past week alone i'v had 3 leechers / afkers also reported them and a simple fix can done done 2 systems that already in the game just needs a little revamp
that being said opion 1 take the pvp counter and add it to the pve mission this inreturn gives u a already working ai it counts your damage dealt / healing this in return
dose your end reward
1st pruple gear
now u add a 5th this is were leeecher ends up as he done nothing he's ranked up 0 damage 0 healing = 0 reward
simple way of using something already in the game
opion 2 there is some kind of counter in pve missions that tell the game what reward u get at the end simpley put u just rework that the same way as opion 1 = afker / leecher get nothing for doing nothing problem solved
now it wont work for all pve content due to somethings are auto given i.e fleet marks and exp but this is were u can change them to like the azur neb / crystal pve were u have to collect a box that contains ur exp marks and reward for team work little more work to do but the end result is the same mr leecher / afker actor get zipo = still solves the problem