I can't see that the NMC would consider these non events as meeting a threshold for investigation.
The patient leaving before being seen - DUs issue on this is that before just documenting that they weren't seen as they'd left, he wanted to enquire from the triage nurse (SP) who'd assessed them whether she had any concerns that she hadn't documented. He couldn't find her to ask so tasked an HCA (Rhianna) to find her and ask the question. Rhianna went off and found SP and they returned to the vicinity of DU while Rhianna related the query. DU waved hi at SP in acknowledgement that it was he who had asked the question and SP said loud and clear in his hearing to Rhianna that she had no additional concerns re this child and it was all fine, before she returned to whatever she was already doing when pulled away to answer this query. His complaint is that she didn't reciprocate his wave or address her answers sufficiently to him, rather than to Rhianna who was the one who talked to her as they walked towards him together.
There was no detriment to the patient, there was no avoidance of answering the question. No information was withheld.
The patient in resus - SP hadn't done all the obs on a patient before DU came into the cubicle, so asked him to do them while clerking the patient. SP left the cubicle.
The patient had obs done, the patient was not left alone, the patient came to no harm and their care was seamless and unaffected. It is not outside a doctor's competence, ability or job role to carry out obs. There will be nothing in contracts or job descriptions that rules obs a solely nursing task. DU has stated that he doesn't have oversight of SP job list and doesn't know if she left to attend to a sicker patient or more urgent task (like giving pain relief to another patient who couldn't wait and SP considered the patient in question in safe hands with DU full attention) .
When you look at NMC fitness to practice hearings these are usually very grave. The incidents above are replicated in EDs around the country every minute of every day.