Not saying you're wrong, it can be quite difficult for a solo inexperienced player. But here's my advice... Do it in a team. Get into the matchmaking channel and form a team (less chance of grief) or take a chance and hop into a pub. Everytime this challenge rolls around I see lots of Limbos in pub index matches so there's a pretty good chance you'll land in a team that can do the job without too much hassle.
To put things in perspective, killing a silver Grove specter isn't difficult either but it involves going around scanning plants and there are people who dislike doing that in a war game... this is probably the group DE wanted to appease when they removed it. So to each his own, can't please everyone.
You also have the option of skipping the challenge entirely and you'll still get enough points to complete the whole NW by season's end anyway... I'm doing that for the stuff I don't like, such as Orb Vallis bounties.