Next sentence addresses that:
> (…) or even using a masked email address service such as the one 1Password provides through Fastmail. Absence of an email address in HIBP is not evidence of possible fraud, that's merely one possible explanation.
It can, but that's kind of the nature of anti-spam systems these days. Come in on a Tor IP with a randomly-generated burner e-mail with a Curl user-agent and you're gonna get blocked from almost anything that spammers have an interest in. Come in on the e-mail address, aged cookies, and a geolocation associated with your credit card for years and you're gonna be fine. Do things in the middle and expect some amount of false positives.
I’ve started using iCloud Hide My Email which generates a random email that forwards to my account email. This assumption is going to cause issues.