There's a related phenomenon I've seen a lot, sometimes firsthand, of people who consider themselves shy while others consider them the life of the party.
For many introverts, maintaining this separate external self requires an act of continuous will, hence the idea that being in social situation drains them of energy. This is especially true the less they socialise: The less practice they get, the harder it is to "play the part" of their external self and the greater the sense of disconnect between the two.
Conversely, the more an introvert socialises, the more easily they can adopt and maintain the external self, and in time it can feel less like an act and more like a different facet of their character. But there will likely always be some sense of disconnection, with a feeling that the internal self is the "true" self, which perhaps only a few close friends and family have access to, and the external self, which is what most people see, is only a mask.
I call myself an "extroverted introvert". I prefer not to engage in social situations that involve more than one or two people at a time. I can function very well in larger social situations, though, and don't feel like I'm "trying" at all. People who have only seen me in those settings tend to think I'm an extrovert.
However, it does exhaust me relatively quickly. Perhaps your explanation is why.
If I remember correctly, he felt as an organiser, he already had a reason to talk to guests and as an organiser he always had an excuse to leave a conversation, which are basically two very common fears of an introverts who still wants social interaction.
You can totally organize parties while being an introvert, it may even be a desirable trait, since a good part of the job is to hide all the gory behind-the-scenes details. For having staffed a few events, one of the thing I find most satisfying is when shit happens (sometimes literally!) and in the end attendees don't notice and leave happy.
So while most people would say someone who doesn't dare to talk is shy, it is totally possible to still be shy and be the life of the party.
As an introvert who has zero stage fright and good talking skills: I am still an introvert. Being around people costs me energy, while for extroverts not being around people costs them energy. I would not be perceived as an introvert by most.
I have a lot of resistance to go and meet people, break ice, try and engage in conversations even with people I know very well or supposed to work with on a regular basis. I feel drained afterwards and need a break after every meeting. The meeting itself usually goes well, and I am fairly engaged even if not the most talkative -- if the subject matter of discussion is my work or something I am reasonably interested in I might be the most vocal even -- and people who meet me (without knowing me and my preferences closely) might very well picture me as a "normal" or even an extroverted person.
But (I just came up with this thougt experiment:) if someone were to interrupt my social or professional meetings at any random point and give me a choice of either continuing or immediately going back to "me time" without any consequences -- I think I would choose the latter 90% or more of the time.
I remembered another friend who seemed entirely different depending upon his girlfriend being around or not. The thing that confused me was I couldn't figure out which version of this friend was the "real" version of him and which was an act - an act for the benefit of the girlfriend or an act for the benefit of the people who only knew him as he was without the girlfriend's presence.
Once you notice this, you can't stop seeing it.
All versions of ourself is still the real us, though -- we're just emphasizing and deemphasizing different aspects of us according to the social situation.
Interacting with unknown people is slightly stressful, you feel this stress yourself but it is hard/impossible to see in others(unless they actually are really bad with interaction). so when self diagnosed most people will say they are introverts, or on the introvert side of the graph(they feel this way based on what they see). but when graded externally would be average or extroverted.
Clearly it is multi faceted / multi dimensional or multi-layered. Like the concept of a persons personality having layers like an onion and few if any know your most interior true self layer.
My wife & I could be perceived as more/less introverted by situation. Work vs family vs friends, talking to known acquaintances vs talk to strangers and making new ones. Who is on social media vs who has 10 text groups of intimate friends they talk to throughout the week. Planning social gatherings vs complaining about plans and wanting to cancel.