From another similar thread, yes only if the organisation is
eagle-eye to spot or is a SOP of the HR of the company (meaning
they have to do a background check on you stated in their company's
policies). eagle-eye here means that although your COS may not
state your PES, but if they are familiar with the SAF vocation,
they might question your vocation hence leading back to your PES.
(Example, vocation like clerk, storeman is in PES C and below, if
they know how to spot, they will ask you why you are in that
particular vocation, etc this kind of question indirectly lead back
to your health)
Again, this might not be a bad thing because it may be just that
the company will tell you striaght ahead that they are not going to
cover for your medical fees, etc. It might be a good thing even,
example, they want to people who do not need reservist due to their
medical condition which means you will fair better than those who
are PES A/B.