In specific search terms in Google, if you use `-site:` and there's a result with "Must Include", it will include the dashes

I have the search query harvard wifi dns -site:pinterest.com -site:githubmemory.com -site:numerade.com -site:coursehero.com -site:chegg.com -site:scribd.com. However, in one of the results, I get this result. How would I get rid of this? -inurl: does not have this problem, though using it may exclude results I may want.