PC brigade out in force..firstly,can we distinguish between SOP violation and unsafe..please...one doesnt automatically entail the other.Secondly,the co-pilots right to command a go-around.Protected by SOP but must be balanced by FAR 91.1 or equivalent.The skipper IS the "final authority".
Having said that........I would say that the stabilization rules are an important SOP and the skipper set a poor example to his co-pilot by ignoring the 500' gate.Somebody said being stabilized at 300' was unsafe..no,thats not correct.Not being stabilized at touchdown is unsafe..unstable at 500' is a SOP violation,but not inherently unsafe.However,not all pilots are test pilots so the powers-that-be draw up guidelines that protect the average pilot from slow spool-up and the danger of not being focused 100% on fp control in the last couple of miles.
The real crime here was not the SOP violations however but the missed opportunity by the skipper to impart some knowledge to his inexperienced copilot.He should have "talked" him down and shown him just how easy it really is.Speed,configure,checklist,ignore profile initially.Recapture profile by 500'.From close-in,it is the only way.No need to take control as this destroys self-confidence.If the poor guy freezes,then you take control and give it back to him when things are more under control.
Airmanship(or CRM for the PC brigade) requires the Captain to help a co-pilot who is floundering.The way in which he does this reveals very neatly his own level of airmanship.