Does the SPRL status mean that part of the house gets designated "business" and therefore tax is payable on that part of the rent? It might be the reason the landlord does not wish this complication. If there are no practical implications like this, well sorry to put a dampener on things, but when a landlord is difficult at the beginning, it might mean trouble to come. That's sounds terrible, just we tried to rent 4 other properties, 1 we actually let go because the potential landlord was adamant he would only offer us a fixed contract, we could not accept it, we spent 3 hours in negotiations trying to reason, his wife said yes, he said no and would not justify why, we walked away very upset, as we really wanted the house, but could not take the risk of a contract which is impossible to break but even more fundamentally a landlord who was difficult at the beginning. We have just moved house where the landlord made our life miserable for the last month..... we were exceptionally understanding when he decided to let himself into the house every day, including weekends, without permission, to do DIY... then on inspection day, lied to the "expert", accused us of breaking things his cowboy builders had in fact broke. We have miraculously now got a house which was not first choice but so far the landlord is simply WONDERFUL, we chose the landlord and then the house.
Best of luck, you will find something out there, even if it is not the first place. I am going to search out the details of the "expert" now who kindly saved us loads of euro on our exit inspection, ironically our crap ex-landlord chose her!