Flush air data sensors generally have more to do with hypersonic regimes (given induced drag forces, heating and so on):
Pitot tube RCS is not significant design driver in say <Mach 2 regimes I believe (especially reading this paper and the calibration and sensoring trade-offs, especially in lower speed less-laminar flow regime)... compared to conventional probe past boundary layer.
Compared to signature of the canopy, flight control surfaces (in operation) and curved surfaces etc. These tradeoffs (for the aerodynamics) bake in lot more RCS return than the pitot tubes I would assume.
I don't know if this author is an expert but it looks like that air data sensors/tubes do affect RCS.
Obviously, the B-2 carries no external/protruting pitot tubes (that would affect the aircraft’s Radar Cross Section – RCS – making it less stealthy); to check airspeed, the aircraft uses static ports set flush into the skin.

This Close Up Photograph of the B-2 Spirit Provides A Fantastic View On The Stealth Bomber's Air Data Ports
This shot exposes a few interesting details about some of the B-2's sensors. The U.S. Air Force has just released some interesting photographs of one of
