Well, the first guy is submitting a patch to the linux kernel source that would make program binaries (executable files, sort of) compiled for an older version of the kernel break. This same guy looks like he is about to argue that it is not worth to maintain compatibility with 30 year old binaries.

And then Linus (the guy behind Linux) goes on to explain that the OS should serve its users, and that keeping compatibility with existing programs, no matter how old they are is of utmost importance for users to be able to use that system.

I don't know if I helped, or if I addressed your doubts. I hope so :)