That is false information ... there are three possibilites for PS2 compatability within a PS3:
1) CECHA/B had the PS2 GPU and CPU combined in one chip on the motherboard and used a bianry called "ps2_emu.self" to launch PS2 titles (resulted in 99% compatability).
2) CECHC/E only had the PS2 CPU on board and emulated the PS2 GPU in software. The binary called "ps2_gxemu.self" is used here. (resulted in 90-95% compatability).
3) Every PS3 after the CECHE models had no PS2 hardware at all and everything was emulated by software. This emulator was introduced when Sony decided to offer PS2 Classics at the PSN Store. The binary called "ps2_softemu.self" was used from FW 1.90 to 3.74. After that Sony switched to "ps2_netemu.self" which is where its at today. And this emulator is not the greatest when it comes to compatability, here is your list:
http://www.psdevwiki.com/ps3/PS2_Classics_Emulator_Compatibility_List