It is , regardless of whether you own the console. It is a copyright violation to distribute this proprietary Sony software. The only legal method to obtain a SCPH-90001 BIOS is to dump (extract) it from your own PS2 console . The process involves using specific homebrew software on a modded console to copy the BIOS files to a USB drive. This method ensures you are legally using the backup for personal emulation purposes.
If you want to get started with setting up your emulator, let me know:
For years, the hacking community had the upper hand.