And Fuji personally I think the controller is wrong. what they are wanting to do is for you to be known traffic for there other stuff and not take the liability for a traffic service. If they refuse to give a traffic service bin them they are only talking to you for thier benefit not yours. Or as what one one ATCO pilot said to one service when they asked what thier operating level was "not above FL100" because he had zero interest in entering into any contract with them
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I think your logic may be a little disjointed, although I am sure not intended.
To be fair the process usually starts with you asking for a service. In open FIR you dont need a basic service, and if you dont want it I guess the answer is dont ask, or positively refuse. If you declare IFR and agree a basic service in hindsight I can see that it is not unreasonable for the controller to expect you to remain at your declared level, even though as Bookie says you have no obligation to do so.
In short if you dont want a a service of any sort dont accept one in the first place.
Also to be fair in my experience most controllers do their best to give a usual basic service - yes sometimes it is for their benefit, and perhaps sometimes entirely for their benefit. On the other hand, for example, I have had a basic service approaching Farnborough on many occasions and asked for a transit. If nothing else it gives the controller an opportunity to co-ordinate you with other traffic as well as their own arrivals and departures. Of course you could ignore them and skirt around their ATZ, even directly under their approach outside the ATZ if you like but what are you achieving?