Someone loitering on the street? In NYC? It's questionable how much attention that would draw.
Also, and not saying this in this case: "Annual Investor Conference Day 1 Agenda, 8am Open Breakfast". Not hard to believe someone would be leaving their hotel nearby at 6.30, 7 for that. It's not staking the place out for hours.
Apparently knowing which door Mr. Thompson planned to use, the shooter arrived outside the hotel about 10 minutes before his intended target and ignored passers-by as he lay in wait.
Yeah. Depending upon the level of prior research by the shooter, the CEO may have shown a reliable pattern before hand attending other conferences too.