Install Windows 10 via Bootcamp Assistant on MacBook Pro from mid 2010
The instructions, you have linked to, install Windows to EFI boot. The Boot Camp drivers provide by Apple were designed for a BIOS booting Windows. In other words, you need to hybrid partition the drive and the instructions explicitly insure the drive is using a fully protected MBR. If you can select EFI Boot of the Windows 10 installation flash drive from the Mac Startup Manager and successfully boot from the flash drive, then you can install a BIOS booting Windows 7, 8, 8.1 or 10 to your Mac. However, you will have to use the command line (CLI) to install. In your case, the graphical user interface (GUI) provided by Microsoft will only allow EFI booting installations.
The are many examples on the web of how to use the CLI to install Windows. For example, these instructions install for a dual boot. Perhaps you could adapt the instructions for your use.