Question about Pure Bloods and House of Slytherin

[potioncat]

Kemper:  
> 
> The status of Muggle and Squib are equal for those who care about 
blood lineage.
> 
> Did I sink your battleship, Potioncat? :)


Potioncat:
No, because again, we have Snape who is friend to the Malfoys and who 
is honored (on occasion) by the Dark Lord. Bellatrix doesn't care for 
him, but I'm not sure if any of that has to do with his Blood status. 

Granted, Squib and Muggle seem to have equal status among those who 
discriminate against non-Magic persons. Of course, we don't see any 
Muggles working for DD. But I don't think it would be unthinkable for 
someone to speak of their connections to the magical family of 
__________ even if the connection was a Squib. Might not mention that 
detail, if it could be avoided.

Cannot get to my DH for canon, but Muriel speaks of families who 
arrange to have their Squib children educated in Muggle schools so they 
can move in the Muggle world. That's not a cold rejection of the child. 
I wonder what actually happened to Marius Black and who blasted his 
name off the family tree? 

Neville's description of his self as "almost all Muggle" makes me 
wonder if JKR just hadn't decided on Squib at that point, or if Alice 
was Mugggle-born.