The Third Hokage had a mean steak going that stretched decades of his life. Proof and point Danzo, who once stuffed him in a barrel and threw him into the ladies onsen when they were teenagers. Now, the Hokage cooes in delight every time he sees Danzo cringe at having to call him Hokage-sama. And of course just because Danzo is also a backstabbing fucker he secretly converts root operatives just for the look he knows will be on Danzo's face when he finds out.
Point, the Hokage was a mean motherfucker who did not enjoy people who fucked around with his village. So when Orochimaru his own student abandoned the village without so much as a "Goodbye hope to see you, fucking never" Sarutobi was reasonably pissed. Or at least that's what he told himself. Then came a sadistic pleasure and need to deny Orochimaru anything he ever wanted. Ever. So that's what he did. He sent ninja out on missions to take serums or plants or people that Orochimaru wanted and kept them for himself. He knew that he infuriated Orochimaru and he didn't care.
So when Orochimaru popped up again disrupting his village and his chuunin exam, the sadistic need popped up with him.
"Ah so Orochimaru wants to continue the chuunin exams?" he mummered. "Well tough, cause I just cancelled them."
Then, he smiled and sent out notices to every ninja in the village that, yes, the chuunin exams were canceled. And then he set up meetings with all the important dignitaries he needs to do business with to crow about what a shame it is but how he simply could not risk their health.
And –despite all the political backlash and paperwork he was going to get –he had a feeling he'd enjoy this very much.
Very, very much.