I have two Sonys and I haven't attached either strap.
The sets are perfectly stable on a reasonable and level surface.
Unless you have kids/pets that will be running into it I wouldn't worry about it.
Frankly, I think including the stability strap is just a Sony lawyer's way of minimizing possible claims from people who have gone out of their way (intentionally or unintentionally) to tip their sets over.
*Edit- I should have stated that neither of my sets are the XBR2/3 but the XBR stands look just as stable as the S2400 stands to me.
The sets are perfectly stable on a reasonable and level surface.
Unless you have kids/pets that will be running into it I wouldn't worry about it.
Frankly, I think including the stability strap is just a Sony lawyer's way of minimizing possible claims from people who have gone out of their way (intentionally or unintentionally) to tip their sets over.
*Edit- I should have stated that neither of my sets are the XBR2/3 but the XBR stands look just as stable as the S2400 stands to me.