I think the conversation is pretty generalized, but I think the President is actually referring to Magneto...
Incidently Rachael never had full access to the Phoenix force, she could tap into it but was not a full merging with it, whether she had the power to destroy something the size of the Death Star is really doubtful.
Jean Grey on the other hand...
But... both are grounded by their humanity and would not do such a thing, more concerned about the 'innocents' aboard the station that did not really deserve to die. Even if they did do such a thing they would be overwhelmed by the psychic backlash of so many deaths.
Unless (once again) it was Jean as Dark Phoenix, and then she would fry the Death Star where it stood, feed of the psychic cries and explosion, then turn on the Earth and consume that as well, and move onto to something else for dessert.
X-Men 0 Star Wars 0. Dark Phoenix still hungry...