I suspect they probably actively try to avoid people that only have one or two installs - there's not enough money in it & casual users are probably more likely

I suspect they probably actively try to avoid people that only have one or two installs - there's not enough money in it & casual users are probably more likely to just abandon the product rather than try to get some crazy licensing deal approved with Oracle (I certainly would). So those users would be reasonably big timesinks with little possibility of phat commissions at the end of it. Much better to make the initial inquiry & find out if their stalking horse of making VirtualBox free has meant it's landed in a large organisation where they might have many installs & they're much more likely to get a big payday for roughly the same amount of effort.