What's a little laser-focused obsession? That can't possibly go wrong. "The assault of Fort Tamblin was to be within hours." And he was clearing behemoths in the meantime so other teams can actually do the rest of the work, a perfectly good way to spend time as it meant he could also search for Genesis in the meantime.. even if it was just listening for a ringtone in the jungle and hoping and dreading to hear it. "How much time does that allow?"

Hollander is an almost ridiculous addition to where he has to go and how quickly he needs to get there, that man was.. insignificant. Less than Hojo, and that took some doing. Hollander is not, however, a high ranked part of Shinra's hierarchy. If he's the problem, then he won't be a problem anymore once Sephiroth found him.

Not with knowing that something terrible happens to Genesis, possibly related to his unhealing wound and Hollander being the 'only one' who could treat it, and Angeal being dead. That leaves one more question as far as he's concerned. It didn't answer everything, didn't answer NEARLY everything, but the rest he could find out when Portal dumped him right where he left to begin with. "...If I stop Hollander, he will not survive the encounter."

He didn't like killing innocents. By all accounts neither did Zack. If Sephiroth's singular means of 'stopping' threats was acceptable, that told him much of what Hollander was capable of.