What's the threshold for abuse?
Can I go for the classic: "it depends"?
If this single merit is all they had from the airdrop I don't think that's a mitigating circumstance. If I sent 200 merits to my alts I bet I'd be tarred and feathered in a jiffy.
Probably

But 200 is enough to go up a few ranks, while 1 Merit is insignificant.
What if I send 1 merit each to 200 newbie alts?
What if I send 50 merits each to 4 Hero alts?
What if I send 5 million merits to a Legendary alt?
Quite insignificant in each individual case.
I'm inclined to agree with The Pharmacist on this. I think it's never ok to merit alts.