Mrs. Norris is a Mudblood?

[honeycakehorse03]

No: HPFGUIDX 57840

Valky:
"It just occurred to me while skimming through COS today that the 
Basilisk attacked a cat first. A mudblood cat? 
Nooooo, can't be. Suddenly, creedence has been granted to a rumour I 
have long ignored. Mrs Norris is a witch. A halfblood witch trapped 
in a cat."

I suppose the attack on Mrs. Norris could be explained with "being 
in the wrong place at the wrong time" and therefore Mrs. Norris is 
only a victim of circumstances, similar to Nearly Headless Nick. 
Although we don't know if NHN was a Muggleborn, so that could be a 
reason as well (But somehow I tend to think that he wasn't because 
otherwise I wouldn't think that he would put so much emphasis on 
being part of the Headless Hunt.)

Now, of course it could also be that Riddle sees Squibs just as a 
low-life like Muggle-borns and therefore was trying to hit Filch 
indirectly. Which brings the question to my head how he would have 
know that? Surely, Mrs. Norris wasn't around when he went to school?

So, I'm going with the first choice that it really was more of an 
accident which had the fortunate side efect of scaring everybody out 
of their wits but also the (surely) unwanted one that it alarmed 
them and therefore made the teachers more careful; even if it didn't 
keep the other petrifications from happening.

Sabrina