Nah - it's only ever an issue with OEM_SLP Keys (and by inference OEM_COA_SLP Keys) - Retail, and OEM_NSLP keys don't even look at the SLIC table.
The BIOS date canonly be an indicator at best - you can have two identical machines from the same manufacturer, both may have a BIOS date of 11/11/11 - one has may have a Windows 7 SLIC table, while the other doesn't. The difference is that the second one shipped with Linux installed, rather than Windows.
Conversely, you can have two identical (apparently) machines with SLIC 2.1 tables - with a BIOS date of 11/01/10 the other with a date of 08/08/09 - the second could be genuine, while the first could be counterfeit (BIOS updated to one released after Windows 7 launched, but SLIC table simulated by a loader.
Fun, ain't it
- and people wonder why I can't produced a Flow-diagram of how to read an MGADiag report!?!