So, a little bit of background information, by default, you hover by holding down the ADS button while in the air. You can turn that off in the controller settings. I personally prefer it off because I only want to hover when I want to hover, not when I want to ADS. So hover gets mapped to the sprint button while ADS.
Snipers increase zoom when you are ADS and you hit sprint. This means that in order to hover with a sniper, you have to change your zoom level. This is pretty game breaking for this control scheme.
As others have noted, the controls for Halo 5 are a cluttered mess. They are going to have to rework either the hover button or the change zoom level button for this to work properly.