This is not a hack. It's a thing non-tech people have been doing for quite some time. Indeed, you can simply call the hotel and ask them if they have any discounts (including event-related discounts) during the period of your stay, and they'll gladly tell you if it means they get your business.

It's always jarring to read something that techies call a "hack" which is something that non-techies consider common sense. What is localfu going to "discover" next? That you can ask the concierge desk to book reservations at popular restaurants?

Correct me if I'm wrong, but aren't those Google Forms? I don't think I'd trust my credit card information to one if it's reminding me not to enter my password in one!

This "hack" appears to just be abusing a conference organiser's pre-arranged rate for hotels near the area. I'm assuming the Google Form submits your information to the conference organiser, not to the hotel. They should (but apparently aren't) cross-reference the attendance list before passing the approved reservation to the hotel.