The decision by President Buhari to seek re-election in 2019 is simply to tell those people, including former president Obasanjo, who dare advice or instruct him not to seek re-election in 2019, that it is within his constitutional right to do so.
And I believe Buhari knows very well that he will lose a free and fair presidential election in 2019. But as someone who is obsessed with Goodluck Jonathan, Buhari wouldn't mind becoming the second incumbent president to lose an election in Nigeria.