There's nothing about ban evasion in these rules. Is it intentional? Or everybody overlooked it?

Isn't that kind of self explanatory? If you escape prison and they catch you, they put you in for a longer amount of time.
I agree it is, but sometimes it's useful to point to a specific written rule. You might
recall that my motivation to the spanish translation was to be able to tell a troll what the rules were. Ok, now that troll has been permabanned but he keeps on creating new accounts, and there's no specific written rule to point to. Self-explanatory and all that, yes, but these people have a
err
different mind set

.