You'd have to make it so the OPs include ethnicity for each lolcow otherwise your script would have to be so complicated it wouldnt be worth it. If your script had to scrape the whole thread then it'll get confused by people discussing ethnicities. Also lolcows frequently say they are a certain ethnicity then years later do a dna test and it turns out to be bullshit. Everyone has different terms for different ethnicities. Black, nigger, etc. You'd have to account for that. Your script would also get confused by usernames that include ethnicities like @Jewish Sex Criminal so youd have to write it to be able to tell the difference between a post and the username/tag.
It'd be significantly easier to just take a stimulant and go through each lolcow yourself.