@Quanosi...
Thanos was only standing at the end of the fight because Odin allowed him to stand; it took 7 panels for Thanos to stand fully...during which time Odin took no action against him.
So yeah, Odin ALLOWED Thanos to stand...
Odin could have killed Thanos if he wanted to; Odin was standing near him with Gungnir in hand and Thanos was on his arms and knees helpless...
Odin could have driven Gungnir straight though the back of Thanos's neck and there wasn't a dam thing Thanos could have done to prevent it...Odin certainly had enough time to perform the execution.
💃