cipher - Why the 'Be Nice' policy? - Clue Eight

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You push the buttons under the letters on the rock wall. Nothing happens for a moment. Then there is a rumbling noise.

gggrrrrrrrRRRRRRRRRRRRRRRRRRR

The rumbling stops. You look around your banana-colored room. Nothing seems to have changed, until you look directly behind you.

There is a picture there:

It appears to be a printed-out screenshot of the 'Be Nice' policy on your favorite site, Puzzling.SE.

You turn it over. This is on the back:

_{liap-liap-lwb lwb-lwb-liap lwb-lwb-lwb-liap lwb-lwb-liap-lwb lwb-lwb-lwb-liap lwb-lwb-liap-lwb lwb-liap-liap-lwb lwb-lwb-lwb liap-liap-lwb-lwb liap-lwb-liap-lwb liap-lwb-liap-liap lwb-liap-lwb liap-liap-lwb lwb-liap-lwb liap-lwb-liap-liap lwb-lwb-lwb-liap lwb lwb lwb-liap-lwb liap-lwb-liap-liap lwb-liap-lwb lwb-lwb liap-lwb lwb-liap liap-liap-lwb lwb-lwb-liap-lwb liap-liap-lwb liap-lwb-lwb-lwb liap-lwb-liap-lwb lwb-liap-liap-liap liap-lwb liap-liap-lwb lwb-lwb-lwb-liap lwb-liap liap lwb-liap-lwb-lwb liap-lwb-lwb-lwb lwb-lwb-lwb-lwb lwb liap-liap-lwb lwb-lwb-lwb-liap liap-liap-lwb-lwb lwb-liap-lwb lwb-lwb-liap lwb-liap-lwb lwb lwb-liap-lwb}

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Answer

The answer is

quartz
look at the bigger image and note all the missing letters. Almost all of them are in the beginning, but the "z" is in "lazy" in the middle.

The wrong way:

1:

apply a ROT cipher and "liab" and "lwb" turn to "dash" and "dot". Morse code, obviously.

2:

After decoding we get the following
GUVFVFPSZCYRGRYVEERYRINAGFGBCJNGVATLBHEGVZRURER

3:

ROT13 gives us:
THISISCFMPLETELIRRELEVANTSTOPWATINGYOURTIMEHERE
Errors are just errors, nothing to do here.