For me it is conflicting. I can't see how you can be both introverted and extroverted but it seems Michael was both. I just can't grasp how this is possible.
Apparently it is possible.
Taking the (16) Myers-Briggs personalities into account(also known as the "MBTi" or the "MBTI test")people function based on multiple cognitive functions , functions based on their personality type.
Michael apparently has been typed as an "ISFP"(Introverted,Sensing,Feeling and Perceiving/Spontaneous) which means that he was a rather introverted individual who made decisions based on (his own) personal feelings(rather than pure pragmatic,rational/objective logic), while being influenced by his surroundings (rather than his intuition) and also while being influenced by his spontaneous tendencies that he had in his personality.
The "ISFP" personality type itself functions based on 4 functions,and the first 2 are its strongest:
1.Introverted Feeling(Fi)
2. Extraverted Sensing(Se)
3. Introverted Intuition(Ni)
4. Extraverted Thinking(Te)
Basically,as an artist/entertainer,he was able to express his own feelings/emotions through his art(music and performances) which points to him using his Introverted Feeling(Fi),but all of this while being aware that he is being watched by an audience,an audience that is going to react to his music or seeing him perform,therefore he needed to make sure that the fans'expectations are met...and this shows him using his second cognitive function,his Extraverted Sensing(Se).
So at least in my opinion,he was not an introvert and extrovert at the same time,but rather an introvert getting a job done,a job that he knew that he needed to get done,and a job that he knew how to get done.