please help with a pshat if you can Todays Daf Kidushin 33b

Todays Daf 
Kidushin 33b

The Gemoro says והביטו אחרי משה The stared behind Moshe "One (R. Yitzchok Nafcha*) is  Doresh this Pasuk לגנאי  They misbehaved  when they looked at Moshe כדאיתא as is 

mentioned."

The Gemoro doesn't elaborate what deplorable act they did.

Rashi explains that being they have done a דבר מגונה   (a deplorable act) the Gemoro doesn't want to publicize it.

Rashi continues that the Gemoro is referring to the Midrash Tanchuma (also Yerushalmi)

that the Bnai Yisrael looked at Moshe and said How fat are his legs how fat is his neck all this comes from us. (our money)

The question we (my Chavrusa) had:

Why would  Rashi publicize it when the Gemoro was careful not to publicize it?

If anyone can help us with a Pshat ,please do so.

*Tanchuma Ki Sisa

The Good And The Bad

We find countless times, Chazal disclosing

the wrongs done by Bnei Yisroel and even 

individuals like נדב ואביהוא or Noach where 

there is a Machlokes if to be Doresh

Lignai or Lishvach. (צדיק -- בדרתיו)

In our case as well both the Yerushalmi and

Tanchuma have no problem disclosing

what the בנ"י said when they watched Moshe.

In the Tanchuma it is actually R.Yitzchok

Nafcha himself (who is the Doresh Lignai) 

disclosing what the בנ"י said (Fat legs etc.)

We must assume that for some reason when it

is part of Limud Hatorah. Chazal held there is no 

problem disclosing both the good and bad equally.

The point our Gemoro is trying to make is, when 

may one sit down after the Nasi passes by

This we learn from the Man Deomar who is Doresh 

Lishvach and they watched

for this reason Moshe walking into his tent.

Usually when the Gemoro quotes a Chazal to

prove a point The Gemoro quotes the complete

Chazal with all the details even if they are

not part of the proof.

In our case the Gemoro doesn't quote the complete

Chazal but tells you " כדאיתא  (the way it says in

Tanchuma/Yerushalmi) "

Rashi explains, the Gemoro omits this

part because it is דבר מגונה and not important 

for our Limud.

Rashi on the other who explains the word "כדאיתא" 

where does it say and what does it say.This is part

of Limud Hatorah to know what the Gemoro meant

with "כדאיתא" In this case of Limud it is perfectly O,K,

to disclose  both the good and bad equally.