Once or twice I've seen Ryanair flight deck crew permit passengers who've complained to use blocked off seats.
Since when do F/D crew do the boarding?
I'm surprised that Ryanair sometimes also blocks off rows when the aircraft is really quite full
This is what we call Rule 1. When the load is 177 pax or less (capacity as i'm sure you know is 189, so it would be a quite full flight), we block off rows 3 and 4 for take off and landing. During cruise pax are free to sit there should they chose to. Hope this helps.
Rgds,
ATS