Speccy will support 10 when one of the following happens:
1 Win10 is released and a new version of speccy is released
2 The betas of Win10 solidify enough to be similar to the final RTM version and Speccy releases a new version.
Officially, in general, Beta Operating Systems and software are not supported by Piriform products, though in practice the developers often are finished with the supporting version before the gold release of the unsupported software/OS