I think what Rasta is saying is that the handset has a regional branding (HTC India) rather than being branded to a network, but the effect for RUU purposes is the same - only RUUs which match this will work without a goldcard (and if you are already on 2.2 then the 2.1 RUU won't work without doing the downgrade trick first).
With a goldcard you can run different RUUs, so it depends on why you need to run the RUU whether this is OK. If it's to fix a software problem, then fine. For warranty purposes I don't know - that would depend on HTC India.
If the Gingerbread RUU does run without a goldcard that should also be OK for warranty purposes. On HTC's UK Facebook page says that it is incompatible with Germany (Telekom Deutschland), North America, South Korea and Japan, but says nothing about India. So you might have that option, but obviously I can't promise that what they posted there is complete.