What do you mean by this? It already reports Linux in the navigator UA, are you talking about the HTTP header? If so, I agree with you and I’m hoping to see a change as it is overkill (although there are reasons against namely passive fping protection in some rare cases).
It causes breakage too, ideally reporting this could influence a change in RFP but there are some blocking issues (things to discuss) at the moment and it is low priority. We could anticipate the change with a patch but we haven’t thought about this yet as we are usually against changing RFP.
Your browser engine is very easy to identify, it would be useless to lie and it would also cause a lot of breakage.