Agree with this in principle - it just makes a potential delay in booting since some of the XT-CF lack a PD resistor on the status line. Delays aren't too much of a concern with 1980s PCs though
How much of a delay are we talking about? More than what would normally be expected for detecting a slave drive?
Can the BIOS simply be re-built to turn on the slave functionality?
Remove lines 136-139 and 163-175 in DetectDrives.asm and then build the BIOS with whatever options you need.