S-corp 2% shareholder's Medicare prem put in W-2 - tax treatment?

[Sabrina1]

S-corp sponsors an ICHRA for employees.  It's my understanding that 2% shareholders of S-corp are NOT eligible to participate in ICHRA, even if they have W-2 comp (i.e., they are not treated as "employees" for fringe benefit purposes).  IRC 105(g), Notice 2002-45.  Alternatively, I believe medical insurance premiums can just be paid directly by S-corp on behalf of 2% owner.   Premiums are deductible by s-corp.   Those premiums are exempt from FICA/FUTA if the payments are "made to or on behalf of an employee under a plan or system that makes provision for all or a class of employees."  I believe this means that FICA/FUTA would not be required withholding on those premiums?  Not sure I'm understanding that rule.

Now assume one of the 2%shareholders is on Medicare and the S-corp will pay those Medicare premiums and put them in that shareholder's W-2.  1.)  Are those Medicare premiums subject to FICA/FUTA tax withholding?  Or just Federal withholding?  Would Medicare fall under the umbrella "made to or on behalf of an employee under a plan or system that makes provision for all or a class of employees."   Any clarification appreciated!