Fake? Not in the sense that someone maliciously added it, no, but that's not what the raw image or film plate looks like either (you have to keep in mind, these were scanned off film plates, they're not originally digital images), and it's definitely not what the actual sky looks like.

Google didn't block anything out, they're simply incompetent at astronomy. They could have used a film plate that did not have Sirius masked, but they didn't know or care to do that. The red film plate they used has sirius masked to reveal fainter stars near sirius that would otherwise be lost in the glare. They could have chosen to use a red film plate that had Sirius with all of its glare, but they didn't.

This is why no serious researcher uses google sky to access sky survey data. It's second hand, it's compressed, it's lower bit depth than the fits files from the scans, and you have no control over which film plate they show you.