Totally agree with your brother. Fill it back up. Those parts were meant to be kept in an oil bath. Why would you leave them dry.
I’m not sure where this idea of leaving the lube out of the lower unit started, but I think it’s a load of crapola. Some guys say oh, there could be moisture in the lube and that water could “burst” your lower unit. I’m calling BS on that armchair mechanic theory. The whole lower unit would have to be 100% full of water to be able to burst the unit if it were to freeze. A little bit of moisture is not going to hurt the lower unit.
And besides, once you put clean lube in, there wouldn’t be any moisture in there at all.
Being of Eastern European ancestery, I have a special gift for being able to see bad s#it before it actually happens. Leaving a lower unit empty with no lube. Hmmmm, now what could possibly go wrong there? Oh, yes, forget to fill it up in the spring and blow out your whole lower unit.
Drain it and fill it. Keep it safe and simple.
Grouse