how is Linus's behaviour not justifiable? The main rule for kernel development is "you don't break userspace' And yet John did. I think Linus is hard on tho

how is Linus's behaviour not justifiable? The main rule for kernel development is "you don't break userspace' And yet John did. I think Linus is hard on those that break this rule because he has stressed this rule time and time again in the past. Also, refusal to own up to a regression is kind of infuriating.