In Star Trek (2009), why was Nero's drill dropped into the water right outside Starfleet Academy?
It just seems a little convenient.
Is it canonically confirmed anywhere that Nero chose the location purposefully?
According to the film's official novelisation, the Romulans specifically targeted Starfleet HQ based on the information they extracted from Pike.
Although there was a cost in terms of operational efficiency (it'll take marginally longer to reach the Earth's core), I think we can assume that damaging Starfleet HQ makes it less likely that the automated defenses could be reactivated. Also, Nero seems almost childishly impressed with how gosh.darned.ironic he's being:
The torrent of tightly contained tornadic plasma that roared forth from the mouth of the Romulan drill platform was directed with precision. As at Vulcan, it could have been aimed at any point on the Earth’s surface. The most practical place for deployment and the one that would have produced the quickest result was the Mariana Trench in the Pacific Ocean. There the plasma would have hissed its way through kilometers of water in mere seconds to strike the planetary crust at one of its thinnest points.
But the individual behind the drill and the eventual obliteration of the planet it was piercing was not in a hurry. It would all be over soon enough, this second induced armageddon, and he wanted to remember it in all its annihilating glory. There was no rush.
Earth’s multiple automated defensive stations had been electronically disabled, thanks to the codes extracted from the admirably stubborn but eventually responsive prisoner Pike. The captured captain had resisted the interrogation manfully, but he was only composed of flesh and blood. He was not even aware that he had surrendered the information necessary to allow the Narada to safely assume its unassailable geosynchronous position above the west coast of North America.
Reports from the drill’s sensors indicated that the city itself sat atop a major but now stabilized earthquake fault. Doubly ironic, then, that it should be the site for the insertion of the Red Matter that would initiate the reaction that would destroy the planet. Ironic, and also fitting. The commander of the Narada was pleased.