For me the event chart may reflect conditions surrounding his announcement: with the positive, expansive Sagittarius Sun – searching for new experience as a group leader, in the 11th House – and fueling its sextile to the Scorpio Moon-Mars, in the 9th, suggesting strategic personal confidence to take advantage of a political opportunity, perhaps. And of course the 1st House Saturn-Pluto, in Capricorn, may reflect his obvious show of formidable personal desire and ambition; strong individual confidence and commitment; and billionaire willingness to spend a massive amount of his own money to become the most powerful, influential leader in the world (Pluto rules the event chart's MC).
I think you put your finger on the question everyone is interested in: How/will his impersonal, data-driven, cerebral personality connect with voters nationwide? I see the event chart's transiting Uranus, in the 3rd, in opposition to Moon-Mars in the 9th, emphasizing this personal dilemma and political tension (referenced by the 3rd-9th Houses) for Bloomberg, and his awareness of the need to address, accommodate, or placate it. And what did he do immediately following his announcement? He renounced his longtime support of the Stop, Question, Frisk policy. Some might call this 'flip flop' pandering, some might call it expedient. However, a natally abundant Aquarian (Bloomberg) - or wildcard, as Dean points out - may be better equipped than most to rationalize contradiction and withstand or ignore uncomfortable feelings caused by it.
I'll be using Bloomberg's natal chart and transits as he campaigns. Hope to check these out more thoroughly later.
Good to see you back on the Forum, Tim.