He was certainly holding a single ear earphone plugged in the telephone set and listening silently.
Everytime there is a cool thing to happen Musk is there.
But WTF is Musk doing here? Is he the new Power behind the Throne?
Does he wants to be the Master of the World (on top of being immortal and brain enhanced)?
[Note: I am replying to your post here on this thread as it seems to belong here rather than on the Russian-Ukrainian war thread and does not involve military matters. I am mostly writing it as a cautionary tale about the sort of speculation that runs rife in our American media on the heels of an election in hopes it will calm the discourse here.]
You don't know anything for certain and neither do I. We were not there.
Numerous mainstream news outlets have reported that Musk walked into the room at some point and briefly talked to Zelensky. Several reported that Zelensky thanked Musk for Starlink, then Musk asked Zelensky how Star link was working out for them, etc., in other words, the part of the conversation Musk was involved in concerned Starlink. Here is one example, from NBC, one of the "Big Three" television networks in the USA (leans left, most certainly not pro-Trump):
Elon Musk briefly joins Trump's call with Ukrainian President Volodymyr Zelenskyy
Personally, I don't see the big deal. These "congratulations on winning the election" calls made by various world leaders are traditionally primarily social calls (similar to the condolence calls made when a former head of state dies) wherein nothing substantive or contentious is discussed, just the usual "look forward to working with you" (or "we are saddened to learn of the passing of your former president or prime minister or whatever") niceties, whether sincere or not. These congratulatory calls are generally upbeat, and the niceties about Starlink are in keeping with that. Other presidents have included business leaders in discussions with other heads of state when appropriate (involved in trade deals, infrastructure projects, etc.) in the past, and will likely do so again after Trump is gone. If all they talked about was Starlink, why the fuss?
As for the alleged call by Trump to Putin, the Kremlin has vigorously denied it ever took place, and Trump's communications director has sort of, kind of, denied it (source is BBC):
Russia denies Trump call with Putin urging restraint in Ukraine
It would be highly unusual (understatement) and against protocol for an American president-elect to call another head of state like that before receiving the customary congratulatory call from that head of state. Well, Trump can be, ah, shall we say "diifferent", but what I suspect is that there *may* have been contact made between Trump staffers and lower level Kremlin officials and not much more.
Major news outlets here in the US have been reporting all kinds of rumors based on "anonymous sources close to the campaign" as if they are fact, but turn out to be untrue. A case in point are all those reports that Trump would appoint Pompeo as SECDEF based on these same "anonymous sources close to the Trump campaign" which turned out to be utterly false.
It's pretty wild, really, but immediately following an election here there are all kinds of players trying gain a cabinet post or similar powerful position, plus those who have vested interests trying to get their names out there or highlight their special interest or issue and "steer the narrative" and so on. It happens to some extent after every election, but is a bit crazier this time around. My advice is to take everything you read in the US media regarding matters pertaining to Trump's plans and doings with a good spoonful of salt until it all shakes out. Right now, there is much speculation swirling around and not so much fact.