Yes. Zinc on stainless steel could make it worse.
There is a mechanism of liquid metal embrittlement when stainless steel contacts with zinc and it is susceptible to brittle fracture especially in fire case. It is common practice to avoid any contact between the two as clearly described in section 4.5.5 and table 4-9 of API 571. )
(Quoted from API 571 section 4.5.5.6)
300 series SS should be protected to avoid contact with galvanized components and overspray from zinc and inorgarnic zinc coatings.)
(Unquoted)
If the bolt is just to open to air (NOT submerged nor internal bolt of process fluid), the use of bare stainless steel bolt will be O.K as oxide film as CR2O3 on ss can protect the surface from atmospheric corrosion.
Lee SiHyoung,
Engineer - Material & Corrosion Specialist
WorleyParsons Oman Engineering,
cap1a79@gmail.com