Sony has successfully removed BIOS packs from GitHub, GitLab, and most standard file-hosting sites. But the Internet Archive operates with a unique legal shield:
Secondly, the availability of PS2 BIOS links on the Internet Archive enables gamers to play PS2 games on emulators, which can be a vital option for those who no longer have access to a physical PS2 console. This is particularly important for gamers with disabilities, who may not have been able to play PS2 games on the original hardware. internet archive playstation 2 bios link
When you turn on a real PS2, the BIOS is the first code that runs. An emulator like PCSX2 cannot legally replicate this code from scratch without risking a lawsuit from Sony. Consequently, the emulator requires an exact dump of a real console's BIOS. Sony has successfully removed BIOS packs from GitHub,