There's no point in assigning fault, just think about prevention for the future.
After some 45 years of sailing, a couple of years ago I woke up on a cockpit floor after being knocked out for 10 or 15 minutes. Several reasons for it (though I don't remember the actual event), but none worth assigning blame, especially to anyone else.
Just be careful out there, and keep in mind that when you jiffy-reef the boom, the boom end might be a bit lower than you're used to with the full main, and you might find this out the hard way.
Beyond this I'll say no more.