Then they should blame the Oni-spooks, not the Spartans, who were just as unaware in that situation. I think alot of the time people seem to forget the UNSC were engaged in super sketchy shit before they discovered the Covenant. In another story, the UNSC would be the evil empire.
But in the universe itself we almost ALWAYS see ODST treating Spartans like shit.
Obrien in Legends constantly whines, grumbles, and gets into hissy fits because he wasn't chosen as the main sniper in the mission, because a Spartan, Cal, was more skilled then him. He resented her even after she saved his ass at least three times throughout the episode.
Major De Silva from the Flood rubs in all the Spartan deaths to chief's face, and calls him an inhuman freak, despite having saved hundreds of thousands, if not millions, of humans over the course of the war.
Dutch calls the Spartans freaks of nature.
There countless examples of ODST shitting on Spartans for no fucking reason.