Look your DH said an opinion when he was drunk. I disagree that people tell the truth when drunk even high functioning drunks, sometimes they just chat shit!
Or when drunk get caught up in something minor that they repeat over and over 🤪 or suddenly start venting about someone or some situation that when sober doesn't usually bother them.
Your DH may be right. Your DB may be bossy- what is bossy really? Unwanted advice and telling people what to do- and your DB may have irritated your DH by what DH sees as overstepping
To you your DB may be being helpful and giving 'much wanted advice and support' and that may be a dynamic in your childhood family relationship that you are perfectly happy with - where your DB feels a strong sense of responsibility and tends to take a lead. Close families can be like that with roles people take on.
Maybe your DH saw your DB as overstepping in some aspect of your life or maybe DB turned a bit of his (perhaps not needed) guidance and advice onto your DH!!
My DSis was bossy. 100% She was also the most helpful, kind and full of advice person I knew so I'd take that "bossy" any time!! I adored her and I was allowed to moan sometimes but never anyway one else!
As an older sister she tended to do research on things I was considering and feel very responsible to give me a bit of "advice" - but others would see her as bossy to me, my own family and to our parents.
I'm bossy as I'm a mum (it's in the job description!) (even when I'm not being bossy and it's just teenagers perception of the fact you're parenting!!). My eldest DS is bossy and even the middle one gives him a run for his money in how much they try to boss me and their siblings around!!! 