The error message ("For a UEFI installation...") clearly indicates that your installer booted in EFI/UEFI mode, rather than in the BIOS mode that Windows XP certainly uses and that Mint probably also used.
The workaround you found will result in a successful installation, but without a copy of GRUB. This is probably fine, since you can then run update-grub
in Mint to have Mint's GRUB detect your Red Hat installation.
As a general rule, though, you want to get the installer to boot in the same boot mode (BIOS/CSM/legacy vs. EFI/UEFI) used by whatever OS(es) already exist. This goal can usually be accomplished by using the computer's built-in boot manager, which is usually accessed by hitting Esc or a function key early in the boot process (before any boot loader or OS-specific stuff appears on the screen). With BIOS/CSM/legacy support active in the firmware, EFI boot managers usually provide two options to boot external media. One option includes the string "UEFI" and the other doesn't. Select the "UEFI" option to boot in EFI/UEFI mode, and select the option that lacks that string to boot in BIOS/CSM/legacy mode.
Note that I've emphasized the word "usually" several times in the previous paragraph. That's because there's no standardization of user interfaces or how BIOS/CSM/legacy options are activated and interact with boot media. Thus, one computer may offer relatively straightforward options for controlling the boot mode of external media and another one may leave you looking like Lex Luthor or Doctor Evil by the time you get it to do what you want. (You'll be equally ill-tempered, too!)
For this reason, my general advice is to not use BIOS/CSM/legacy support if you can help it. The boot process on most EFI/UEFI-based computers is much more straightforward if BIOS/CSM/legacy support is not activated. Of course, going EFI-only is not always possible. In your case, Windows XP doesn't support EFI-mode boots (at least, not on x86 or x86-64 computers), so you pretty much have to use BIOS/CSM/legacy support to dual-boot it. I mention my advice to go EFI-only for the benefit of others who might be using Windows 7 or later rather than XP, or in case you want to make changes to your setup in the future.