And exactly how much separation would normally be provided for VFR traffic by ATC in Class D airspace.....?
(A) None, possibly with a smidgeon of;
(B) Duty of Care.
But both of the above rely on it being a known traffic environment, i.e. ATC know what everyone is doing. Once an infringement occurs it becomes an unknown environment because ATC has no earthly idea what the 'rogue' aircraft will do...in exactly the same way that none of the airlines nor the other GA has any idea.
Effectively the 'controlled' airspace now has an element of the 'uncontrolled'. ATC will do it's best to separate all the other traffic from the 'uncontrolled' aircraft (this may well be less than "standard" separation but it's better than nothing!) whilst maintaining separation (where required) between the known traffic.
Would you honestly prefer if ATC told you "Unknown traffic, 1 o'clock, range 3nm, I think it's a PA28, possibly crossing right to left, maybe turning towards you, no height information available. Cleared to Land"??
I'd say, given that you, nor I, have any idea what was going on in the cockpit of the infringer (Head down? Head up? Emergency? Equipment failure? Weather deterioration? Pilot experience? Malicious intent? Etc, etc), that the actions taken by ATC (clearing the runway, holding aircraft) seem pretty appropriate. That we are talking about delays rather than an AIRPROX (or worse) suggests to me that the situation was well-managed.
(Also bear in mind that, whilst RT exchanges between ATC and the various aircraft being provided with a service can be overheard, there was probably a lot of unseen work going on in ATC, e.g. Extra eyes trying to track 'rogue' aircraft, telephone co-ordinations between the Tower and adjacent units, alerting the aerodrome fire service/aerodrome authority to prepare for an emergency.)
Re: book-throwing... That is unlikely in my opinion to have a significant long-term effect on infringements. Infringements (vast majority) are unintentional errors. Pilots don't set out to infringe CAS. Improved use of LARS, "listening out" frequencies/codes, etc, is more likely IMO to reduce the number and severity of infringements. Some ATC units and local flying clubs/local operators have good, constructive dialogue - this is surely what we should all be promoting, rather than debating whether the ATC service, based on the classification of airspace, was appropriate.
(Supportive Class D ATCO)