Plus if the other 5 bedroom house you did find was far away that would not be acceptable either.looking at that case, I try to see how easy it would be for someone to find today a comparison in my area, for a 2 bedroom apartment. In the small towns surrounding mine (5 towns) with a population of more than 64k (north Dublin), 5 ads today and 0 for a 5 bedroom house. So I can imagine that finding another 5 bedrooms house in a more remote would be close to impossible.
The only answer for a landlord is never, ever raise the rent. This is presumably the situation the RTB is trying to engineer. You can never evict no matter what and you can never raise the rent either.