Paolo VI was born at Concesio near Brescia and during his career was Archbishop of Milan so there are organized trips from both Brescia and Milan. As far as I am aware he has no special link with Florence so any tour party would likely be privately arranged and hard to find out about. But with the fast train from Florence to Rome it is easy to do the trip by oneself but get to Rome early as the square will fill up very early.
If there plan was to be in Florence on that day, maybe it doesn't make sense to head down to Rome.
If they do want to go to Rome, then it makes more sense to get there the day before so that they can be in place at the Vatican early... so early train from Florence is going to get them there early enough to get into the piazza.