Hamlet has the right to feel hesitation towards killing Claudius. He wants to kill Claudius at the right time to assure he will go to hell. Hamlet is put in a situation where he needs to take his time carefully before preparing his steady assault. He's taking this mission with care knowing Claudius is praying to cleanse himself from the sins he made daily. It is more significant for Hamlet to get his revenge thank what others would accuse of him being a madman.