Not so sure what the side slipping limits may have been in the real aircraft though
Test pilot of the 707 Tex Johnson quotes a yaw limit of 15° and cites the exceedance as being the cause of the loss of a Braniff 707-220
The resulting crosswind on the vertical tail forced the rudder to full deflection, overpowering the authority of the rudder control tab. The resulting extremely high roll rate created severe centrifugal loads, which caused engine attaching structures to fail, and three engines separated from the airplane.
Could have been describing the subsequent loss of the RAAF 707.