Trademarks are limited by default. Infringement is only an issue if a) it’s a wide known brand b) They’s any form of confusion.
a) is not the case. Kik is not widely known
b) There is no way you can confused a piece of code with a messenger application.
So, Kik really did not have a case. They used the normal scare tactics, with a reference to trademarks / lawyers / DMCA.