Speaking yesterday after a tense Labour Relations Commission meeting, Siptu organiser Anne Egar said any breakthrough in the long-running dispute could only take place once this situation is accepted.
Ms Egar said if Mr Ronan had a legal obligation to pay the additional funding, the union would have gone to court immediately and the issue could have been resolved before Christmas.
However, she said that while the 32 affected staff have a collective agreement, it is not enforceable in Ireland — meaning the moral argument needs to be stressed.
Since the dispute began, the workers have organised a sit-in at the Cork facility to ensure they receive enhanced redundancy payments they say were promised by Mr Ronan.
The State has already paid statutory redundancy of two weeks per year of service to the employees because the Vita Cortex industries company said it had no funds.
The workers argue that they are entitled to 2.9 weeks per year of service, and have said they will not end their occupation until the additional 0.9-week payment is paid.
Last week, Mr Ronan offered an overall payment of about €180,000 to settle the stand-off, which RTÉ said was raised by pledging some of his personal assets.
However, the €180,000 is about half of the outstanding €372,000 which the union is seeking.
SIPTU rejected the offer as “derisory”.