Voyager was his first job out of the academy. Every non Maquis Ensign had seniority over him. Every noncom and enlisted crewman probably clocked years on him in experience, remember Miles and Julian in the beginning? they may have to follow his orders but he's really just getting in the way of jobs they know how to do perfectly without oversight.
Seniority is how officers of the same rank, baring orders, work shit out, so I have no idea what this "tactically superior ship" bullshit is about from why Janeway who, depending on the conflicting canon you want to site, was also on her first mission and first command, when Ranson had been captaining in the Delta Quadrant 6 months longer than she had been a Captain period.
A superior officer can just switch commands.
If he wanted Voyager and she thought the order was legal (Fuck "just" it only matters if he had the authority.) she would have had to have given it to him or whosoever he wanted to replace her with which probably would have been Max Burke and she would have been reduced to Commander (Just Like Decker when Kirk stole the Enterprise.).
For Fucks sake a 1/4 of her crew were Maquis terrorists!
They finally didn't need the Maquis and they could have used Equinox as a prison barge, leaving Voyager just full of proper officers, if that is that they just didn't turn one of their holodecks into a jail.
Kim was Supergreen.
The Captain too.