When commuting I nearly always have 1 pannier on the left with a heavy notebook, some clothes and misc junk.

I can easily ride no hands to put on gloves, zip/unzip jacket, etc.

The only time it matters is when I am not on the bike. It's harder to balance it against something to stand it up.

Anyone who rides a bike moves around to balance.

Tell him that's he's a dangerous fool for having his keys and cellphone on the same side. It makes just as much sense as his theory.

In theory, there is no difference between theory and practice. But, in practice, there is.

Joe