We have seen Jon Snow through different seasons of Game of Thrones, leading different groups and bringing them together without violence (or at least tried to avoid when he could).
On the other hand Daenerys has always brought fear to her people while leading them (bend the knee or Dracarys). Moreover, Daenerys asked Jon not to reveal his true identity in S08E04. One could argue that if she really was a good ruler she would simply leave the claim to the Throne to the true heir.
Jon has been with Daenerys for long enough to know her perspective in a better way. Still, why does Jon blindly trust Daenerys?