It is a Psalm asking for vengeance. The psalmist is asking for the literal death of his enemy. Not just that his enemy would be taken out of power, but that his enemy dies -- leaving his children fatherless and his wife a widow. Pretty hard to put a different spin on that.
6 Set thou a wicked man over him: and let Satan stand at his right hand.
7 When he shall be judged, let him be condemned: and let his prayer become sin.
8 Let his days be few; and let another take his office.
9 Let his children be fatherless, and his wife a widow.
10 Let his children be continually vagabonds, and beg: let them seek their bread also out of their desolate places.
11 Let the extortioner catch all that he hath; and let the strangers spoil his labor.
12 Let there be none to extend mercy unto him: neither let there be any to favor his fatherless children.
13 Let his posterity be cut off; and in the generation following let their name be blotted out.
It even calls for harm to come to the leader's wife and children.
My personal opinion is that Speaker O'Neal is an idiot. I don't think at all that he was calling for the death of the president -- no matter what he might personally think, that would be absolute political career suicide and could put him on trial for treason if anyone thought he was seriously asking for that. IMO he thought he was being clever, and used a Bible verse because he thought it would appeal to his Christian constituents ("oh look, here's a verse in the Bible about someone else taking office -- that applies to Obama!") without looking at what the passage really says at all.
Lots of people do that, especially with Old Testament scriptures. They either gloss over or ignore the violence, or they embrace it and use it as an excuse for their own violent attitudes and actions.