So, you just answered your own question. Assuming Mjolnir did the job for which he was employed, there would be no reason for him to return the money as the question as to whether he agreed with his employers politics or even if he liked them is irrelevant. That would be like saying a prostitute should refund a client's fee anytime the hooker did not enjoy their company. The real question would be why someone would work for someone they despised but that would likely generate thread drift not since since we last learned the alleged nature if Grace Jones's lady parts.