"And afterwards I was very glad that the coolie had been killed; it put me legally in the right and gave me a sufficent pretext for shooting the elephant." Explain.

The elephant's killing the coolie gave the man an excuse for killing the elephant. He was asked to kill the elephant for that reason alone and would have been looked down upon for killing it for any other reason. Thus, he was happy the Indian had been killed at the bazaar because he wanted to kill the elephant. The collie's death was his justification.