re: Crackpot ASOIAF Theories SPOILERS

Still chipping away at my re-read of ASOIAF while reading with the SO who is on his initial read. Getting into the thick of SoS. Just finished reading about Robb sending his succession letters with Lady Mormont and the others to Greywater Watch. Can't help but feel that it's a plot device to secure Jon's claim should no one outside of Jon/Howland Reed/etc know of Jon's R+L lineage. Or that it doesn't frick up Littlefinger's world when he tries to make claim to Winterfell through Sansa.