Point No.1 - Sushant may be good as a worker, as an individual lone contributor who by the sheer presence of his talent, skills, perseverance and hard work has worked his way up the ladder in his current manufacturing organisation. However Sushant should realize that talent and technical skills alone is not good enough. As one grows in the organisation and the number of years pass by, demands of the job and the organisation vary, they change. So one needs to adapt to it, develop themselves as per it. Repeatedly being in the same profile will not help.
Also by virtue of being in the same organisation for the past 12 years since the start of it, one tends to develop a laid back attitude and of being that in a comfort zone that nothing will happen to me as seen in the statement by Sushant to his boss Ravi that he has seen many bosses who have failed to control him and ultimately left the company. Sushant is also comforted by the fact in the back-end that he is the blue-eyed poster boy of Mr. Takimoka, Operations Head from Japan who had deep interference in operational activities of the manufacturing unit.
Point No.2 - Mr. Takimoka took a conciliatory approach in this matter. Their Indian counterparts Mr. Ravi and Mr. Gopalan had decided to take the matter of Sushant hands on and had decided to confront him and also show to him as to who is the boss. However, since the matter was reported to Mr. Takimoka who always had a positive report about Sushant and was impressed by his work decided to speak to Sushant alone, calm him down, may be give him some guidance, tips on how to get along with everyone by improving his behavior including his seniors as it would be good for everyone in the organisation, it would be a win-win situation as compared to a confrontational approach.
However Mr. Takimoka knew that time was running out from him, Sushant's matter had indeed become grave and there was not much he could do to control the damages as Mr. Gopalan the manufacturing head had reported that due to Sushant's behavior and inclination to not follow systems and processes, the organisation had lost 3 DGM's in the last 5 years. It would be a matter of time that the organisation would have to let go of Sushant if he did not change or improve his behavior and look for a replacement. As ultimately, systems and processes are important; those define an organisation and not an individual.
Point No.3 - Gopalan was going to take the HR head into confidence and was going to brief him about the incidence. However, he saw an email from Sushant apologizing about the incidence that had happened and the underlying factors that led to it. Since the matter has come on record, on mail, Gopalan should still speak to the HR head about it including with Ravi and give their views also. Let the HR head then take a judicious call. Sushant's mail should also be replied to. Since Sushant has apologized, everyone can move on but care should be taken that such instances do not repeat again.
Sushant should be informed to improve his behavior and attitude. Maybe some sort of coaching and mentoring in behavioral attitude can help Sushant. Also since Sushant has said that he was engaged in various jobs for the past few days and was pursuing it passionately at the cost of his family and personal life, all his 3 seniors should have a meeting with him and see if he needs a helping hand so as to reduce his workload and thus work pressure. That will perhaps lead to Sushant being in a better frame of mind and thus in behavior also.
Point No.4 - No, I don't think Ravi should change his functioning style keeping in view the prevailing relations dynamics. He was right in asking details directly from the graduate engineering trainee (GET) when Sushant failed to provide it to him in spite of regular reminders. Ravi was also right in knowing as to what the reportees under him were going about doing their planning work and how are they going to deliver. As a boss, he has the right to know as to what his subordinates are up to. Ravi was also right in reminding Sushant how he had failed in his other duties of taking the AM along with him during visit to Tooling Vendors but did so alone. Ignoring your reporting authority's instructions repeatedly is not a good sign of things to come and hence Ravi was right in his actions.
Sushant should learn to respect his seniors, his colleagues instead of confronting them verbally or by not following their instructions. If Sushant did not enjoy reporting to either Ravi or Gopalan, he should make it explicitly clear and try to work out a solution towards it. Either sit with them and tell to them what he sees are right or wrongs in their working relationship and also listen to their views and see if some amicable solution can be worked out. Else, Sushant can go for a change of profile or reporting authority.