Only holidays that fall on a Sunday are pushed to Monday. It does NOT happen to any other day, and has no precedent at all. If Monday is a holiday - as will be the current case - then the holiday that would have bounced off sunday will get 'abosrbed' into Monday. So Monday in real terms is a "double holiday" squeezed into ONE day!
So 27th Dec is a normal working day plse report to work. On the bright side, parking spaces will be plentiful and there will be no jam as many Kenyans will still be in marigo-ini or mboco-ini
So your initial assessment of resuming on 27th was entirely correct - disregard what that fellow was telling you.