Upvote:1
Timatic tells me that a transit through Ireland on separate tickets by a person holding a passport from the Philippines requires a transit visa. The airline will check Timatic at check-in and may deny boarding if Timatic tells the check-in agent that the passenger does not have required documents or may be refused entry.
Note that Dublin airport is the only airport in the EU without an airside transit area. Everyone transiting through DUB has to go through a passport control regardless of whether they are transiting or entering Ireland. There is, however, a specific passport control used (almost) exclusively by transiting passengers, so officers at that control will be expecting transits and may be more lenient, given that he is transiting to his home country.
He is likely to be denied boarding at MCO if he attempts to fly on these tickets. At this point your best bet is to change his bookings.