Did Snape defend trio at the end of PoA? /Are appearances important to Snape?

[a_svirn]

No: HPFGUIDX 142211

> colebiancardi:
>> really?  I wish I had PoA on me right now.  I was under the 
> impression that Snape never heard that PP was an animagus; that he 
> only heard about the Prank and then appeared in the doorway.
> 
a_svirn:
Well, you are wrong here, he came in when Lupin started his tale. 
That's when the door cricked and the kids suggested that that was 
because the place was haunted. So he stayed and listened the whole 
story about the Marauders becoming animagi. 

> colebiancardi:
> And I never got the impression that Snape was going to hand over 
> Sirius to the dementors by himself.  I was under the impression 
that 
> Sirius would be turned over to MoM and they would determine 
Sirius's 
> fate.  

a_svirn:
Perhaps the film's contamination? In the book Snape left no room for 
interpretation: 

"Up to the castle?" said Snape silkily. "I don't think we need to go 
that far. All I have to do is call the dementors once we get out of 
the Willow. They'll be very pleased to see you, Black... pleased 
enough to give you a little kiss, I daresay..."

Besides, if that were the case, why would the Trio attack him? 

> colebiancardi:
>As far as silencing the Trio, it could be that Snape was 
embarrassed 
> by the whole event in the shack;<snip>

a_svirn:
Don't you think that he choose a very strange strategy to avoid 
the "embarrassment"? He exposed himself as unbalanced not to say 
deranged person before the minister. Surely it was even more 
embarrassing?