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.
There is no need for any individual to have alt account instead to spam signature campaigns.
Allow me to prove you wrong:
LoyceBot and
LoyceMobile don't spam and don't have a paid signature.