I have no problems with the FAI linking these games to the Block Booking scheme.
However, for friendlies, they should offer a loyalty scheme to Block Bookers by discounting tickets by say 20%, i.e a 50 euro costing 40 euro. Then, if a Block Booker did not want to take the discounted ticket, they would lose their block booking.
This would gives a happy balance between the FAI keeping a reasonable level of revenue and Block Bookers would get benefit and recognition for continued support for every game.