Stupidity? I don't think she has an issue with him trusting Davos, she just doesn't know him well and to be fair Davos DID advise Stannis who lost every battle he fought. Also, Jon wants to march on Winterfell with like... nothing. She knows she can get more troops, so she's doing so. Don't see the stupidity there. If anything, Jon is being too reckless after coming back from the dead. He trusts too easily and he feels invincible. Not going to end well for him when he faces Ramsay and the Twenty Good Men...