First is likely working as intended given it's how all the other enmity transfers.
Maybe working as intended, but maybe not.
I think its much more likely that they didn't even consider how much enmity pet self-buffing moves should generate. Mobs don't have any enmity generating special mechanics, because players choose their own targets.
When they overhauled bst ready mechanics, they boosted them to be like weaponskills. but I'm confident they didn't even ask if they SHOULD adjust enmity and just left the buffs at the default of 1.
Sure, you can say its working as intended if they never intended anything else, but I'm pretty sure they 'fixed' other things in the past that were obviously just not designed for, but were good ideas.
shucks, back in 2012 and 2013 I made several discussions on se forums suggesting that pet ready moves should skillchain, because blu used monster moves to skillchain, and smn and pup can both skillchain w/ pets. It seemed a natural, and consistent adjustment to make. someone over there must have thought it was a good idea. I wasn't even hoping for a boost in ready move damage. I just wanted to open w/ ready move and close w/ master at the time for skillchain fun.