MCC is a requirement for a first type rating on any multi-crew aircraft.
As a multi-crew type rating is a requirement for holding an EASA ATPL, it stands to reason that, if you have an EASA ATPL you have met the requirements for MCC.
This sounds like a typical HR balls-up where the left hand doesn't know what the right hand is doing. Someone in HR, whose only knowledge of aircraft is sitting in comfort in company sponsored first class travel, has written a set of requirements for employment, constructed from the basic EASA requirements but hasn't bothered to read the exceptions to the rules, whereby a person already holding an ICAO Annex 1 ATPL, and meeting ALL regulatory and/or experience requirements for EASA ATPL issue, can obtain an EASA ATPL without undertaking a MCC course.
i would wager (notionally, of course) a month's wages that you can provide the 'rules and regs' to the jobsworths at this airline but it will not make a scrap of difference. "These are OUR rules, not EASA's"...or in other words "It is far too much like hard work for us to spend two hours rewriting our internal policies to take into account EASA's actual licensing requirements - our own are much easier".
Saying that, I may be being a tad unkind to the HR department when in fact the problem lies with that vile breed of low-life known as 'insurers' who spend a large proportion of their existence introducing legislation forcing insurance upon us, whilst spending far more time writing exemptions and 'get-out-of-paying' clauses....and breathe!
It wouldn't surprise me if somebody within the airline's insurance/legal department has dreamt up this requirement, having no real knowledge of the exceptions within the EASA/EU regulations!
Soap box away...coat please!!