Why does their marketing website need to be HTTPS-enabled? I mean, they will need to do it to appease Chrome in a few months, but really it has no effect on just about anything. They don't administrate the drones through their marketing front page.
The website has other problems though, mainly the excess of effects and reliance on hover states for presenting useful information. Nothing that HTTPS is going to fix.
Marketing sites often provide contact information for your organization. A MITM on your marketing site means Mallory can alter your contact details and potentially intercept your communications.
This is one reason to enable HTTPS on your marketing site. There are many many others. What reason do you have for not enabling HTTPS?
The website has other problems though, mainly the excess of effects and reliance on hover states for presenting useful information. Nothing that HTTPS is going to fix.