Is _Debian GNU/Linux Installation Guide_ current?

[Richard Owlett <rowlett@cloud85.net>]

I wish to install Debian 10 on a laptop with no internet connectivity 
following instructions at

https://www.debian.org/releases/stable/amd64/ch04s03.en.html#usb-copy-flexible

The system I'm using to prepare the flash drive is running Debian 9.13 
{the i386 flavor IIRC}

It responds
> root@defaultinstall:/home/richard# install-mbr /dev/sdc
> install-mbr:/dev/sdc: Probable detection of modern MBR format which is currently
> incompatible with install-mbr.  Installing will probably break Windows installations
> on this system.  Use --force to override.

Is this expected?
TIA