He gives many reasons. for example, when entering the water with double and a stage he thinks that there are to many places for fins to get hooked on thus tripping in the boat.
I agree that walking around on a rolling and pitching boat deck with doubles and a stage in fins can be a challenge.
However the best way to address it is to get to the rail or exit point sans fins then lift your foot, have a crew member or buddy put the fin on for you, repeat with the other foot and then go over the side with both fins on.
There have been tech divers who have died jumping in with air off in a dry suit while over weighted. You drop like a stone, the squeeze on the suit restricts mobility so you can't reach your tank valves, and you just keep going to the bottom where you stay until they recover your now lifeless corpse. Deciding to jump in without fins just extends the potential for you to kill yourself in this interesting way to situations where you are only slighty too negatively bouyant.
Always check the regs right before you go over. I had a well meaning but slightly confused crew member turn off both posts, just before I went in about 3 weeks ago on a dive with heavy curent where I wanted to go in negatively bouyant. A just before I stepped off check of the regs pretty much saved me from an interesting yet stressful moment. Going in with no fins and no gas, would have greatly magnified the risks.
Similarly, you never want to go in with your fins off under any circumstances as it severely restricts your ability to tread water or swim if the situation requires and is essentially removing tools from the tool box that you might end upo needing.
Plus, more than on diver with a stage has had the stage come up and try to smack him in the face on entry, especially on a larger boat where the drop may be 5 or so feet to the water. If you are holding on to your fins, what else are you not holding on to? When entering with a stage, I hold it down with my left elbow over the top of the valve with my left hand securing the reg and mask. It leaves the right hand free for the boat until I jump and leaves that same hand immediately available for grabbing the current line.
No offense here but your buddy has an awful lot to learn and needs to get his stuff together and start thinking through the whole evolution before trying to solve what is a minor problem by creating 2 or 3 more much more serious ones.
Stop listening to him and maybe start helping him see the big picture before he gets himself hurt.
At this point my opinion also is that he has no business diving with doubles let alone a stage until he gets squared away on some very basic skills and develops at list a minimum degree of critical thinking ability.