Now see if chattr +/- i ... works on your K5
Not even 'root' can deleted a file or directory with 'i' set on it.
Best that I know, mmcblk0p3 (a.k.a: /var/local) is mounted at the same point in the file system in both 'main' and 'diags'.
I.E: It is common to both of them.
So if we take over an increased size /var/local for end-user applications . . .