To be fair to Rufus I don't think his plans to deal with Sephiroth were unfounded. Yes the rocket attack didn't work and probably wouldn't have even with the huge materia, but Rufus is clearer a survivor. He fought pretty damn hard to deal with WEAPON and to break a hole into Sephiroth's hiding place. It's only because he was so badly injured and Shinra went to pieces that no further action was taken. I'd assume that if Diamond WEAPON hadn't blown the Shinra building halfway to hell Rufus would have mustered all his forces to storm the crater and attack Sephiroth. If not that, it's silly to assume he didn't have some sort of plan, and that the plan actually had (some) chance of succeeding.
Sure, Avalanche was probably the only group of people capable of defeating Sephiroth, and it all would have been for nothing anyway if Aerith hadn't manipulated the lifestream, but Rufus was working with the knowledge and resources he had to try to make a difference. The fact that he's a murderous jerk with zero concern for the planet's well-being beyond his own survival doesn't necessarily devalue his actions.
All that said, I think it's a fair claim that Rufus had no reason to put much stock in Cloud and company's ability to stop Meteor. In a lot of cases the gang just got lucky, and in a world-ending crisis I'd sure as hell hope that a mobilization of wealth, technology, and weapons used intelligently could help avert disaster. Everything Rufus did in the game was logicaly sound from his perspective - it's just that some of those decisions were cold-blooded or failed due to circumstances beyond control. Hell, if I blasted a space-rock with a rocketship stuffed with materia that probably had nuclear-level force, I'd be pretty damn shocked when the meteor just pulled itself back together.
Shinra's plans didn't fail because they were bad plans, it's just that Sephiroth and Meteor were much more powerful than anyone realized. Even the heroes were at a loss when Holy activated too late. If not for Aerith their plan would have failed too, and no one, least of all Rufus (or even Sephiroth), was expecting the lifestream itself to rise out of the planet and save everyone in something so miraculous it could be considered an act of god.