Official comment
We do not have a way to prevent them from submitting the form, but you can certainly automate filtering them after they have submitted the form. This does give you a second chance to get them to sign up with their company email address.
After a form fillout, a Campaign Condition can check to see if their email address contains something like "gmail.com" or ".ru". You can have as many conditions as you want.

The "No" path of this Condition would get the normal email, while the "Yes" path of this Condition can send them an email with instructions and a link to sign up with their business email, and then set their Bulk Email Status field to "Transactional Only" (opt out). Or tag them for deletion later.