I don't totally agree but I think something needs to be done.
I don't agree for the reason that when you are legit and need to swap characters or something like that during a strike (which people do all the time in nightfall and weekly heroic) a kill counter could make or break your entire strike and ruin it for everyone.
I think a good sense solution would be to have a strike report counter against the players who constantly AFK. The counter would not kick them or limit them from strikes but something along the lines of them being removed from the group once the group passes a checkpoint after 60 seconds or something if they have x number of reports against them.
This way the only time the person is really kicked from the group is if they are actually AFK and so long as they are keeping up and productive they won't be removed. This would also stop potential abuse by habitual reporters.
Kwesdog