[Formendacil]

In addition of any matter of slighting Boromir--I can take or leave that, since I can see Boromir being more than okay with going home his own way (Gap of Rohan, etc.)--there's also the fact that Aragorn is headed for Minas Tirith. It's worth remembering that his goal is not to go with Frodo to Mt. Doom, but to Gondor. Quite apart from any miracles in getting to Rivendell, Boromir's arrival is a godsend for Aragorn (and Gandalf and Elrond and anyone else behind the scenes) because their journey together gives Aragorn the chance to make Denethor's son and heir an ally before he ever arrives in Minas Tirith with his groundshaking claim. Quite unfortunately, that's not exactly how things played out.