Why Uriel chose to share the rewards for killing the cryptid he killed practically on his own was a mystery to all of those who witnessed the deed. It was a dire fight against all odds and if he had decided to claim the entire reward for himself and even demand a hefty compensation for saving the Defenders no one would have hold it against him.
Him offering to split the reward wasn't just generous but altruistic, which was highly against Uriel's character which got Nika to pester him for an answer on their way back to the hotel they were staying at, which luckily was located in a part that remained untouched by the Culebre.