Wordy mc-fucking-word. I recently ranted about that myself and only hope that fandom at large can nip this annoying little trope in the bud before it devours us all.

Parents and older siblings get to call you things that no one else gets to use, especially belligerent strangers in a cage. The use of the Sam/Sammy dialectic in the pilot was done for a purpose, as you eloquently explained, and once it was resolved it was resolved. Writers need to get past it and realize that character shorthand of that nature is sloppy and leads to shallow emotional representations.