Actually I agree i don't like it I also get compare to my 10 years older sis it's annoying now for me too see face similarities but ability differentiation that i hate thd most , comparing someone is actually hurtful but beta himself decided to bargain into this window omega can't say much about it.
it's his brother tho (i would accept it if its a different person), as a child with siblings it kinda hurts to be compared like that yk. They're different person but the fact that he always does compare them instead of being grateful is kinda sad. But it's fictional and as you said, he's still grieving so it's understandable.
I don't like how the omega compares ML to his brother like bruh