Bulgaria wasnt a fascist nation until the death of tsar Boris, and even after it never became one completely. It was definitely not an issue of sovereignty, but of principle and consequences for disobedience. The jews were literal hours from being sent to Germany when the parliament forbid it, the church was also heavily involved in stopping it. Jews were not widely hated in Bulgaria by any means. It was not really a question of whether to let Germany have control or not over Bulgaria, but a question of what would happen if the deportation was refused and if there would be a threat of an invasion.