Siskos prejudice?

[Tosk]

insulting him

When did he insult him?

Assuming that all of a race is going to act the same is prejudism.

When did he act like an entire race was going to act the same?

Sisko "Look, Nog, I have to be honest with you. When I think of candidates for Starfleet Academy, yours is not the first name that comes to mind."
Nog "Why not? Because I'm a Ferengi?"
Sisko "Not at all. The fact is, your reputation on this station leaves a lot to be desired. Your school grades are mediocre at best, and you've had more than a few run-ins with Constable Odo."

And if you need further proof, Sisko's attitude immediately after the meeting.

Dax "I always thought it would be interesting to have a Ferengi in Starfleet, but Nog?"
Sisko "I know it seems unlikely, but before I make up my mind I want to give him a chance to prove himself."
Dax "Commander, there's a lot of valuable equipment in cargo bay twelve."
Sisko "I know."
Dax "Maybe I should assign a couple of crew members to assist him."
Sisko "No. I want him to do it alone. No help, no interference, no one looking over his shoulder."

That's Sisko, despite every reason not to, giving Nog a fair chance. Not just a fair chance, but such a fair chance that even Dax thinks it might be unwise.

My opinion will not change.

I don't care if it does or doesn't. I'm only arguing against what I see as some possibly faulty assessments that lead to that decision.

 

[Oddish]

Here's the real question... if Nog had been human, would Sisko have similarly hesitated?

I think that yes, he would have.

 

[at Quark's]

For that matter, even after he joined Starfleet, Sisko sometimes found it necessary to get angry with Nog to get him to cooperate (Homefront/Paradise Lost over Red Squad springs immediately to mind, but might not be the only example).

True, but I doubt Sisko would've acted any differently in that situation, had it been a human (or any other established Federation species) ensign that came from DS9. He was rooting out a conspiracy by any means necessary, and the ensign he could use (who just happened to be a Ferengi) was in danger of falling under the spell of that Red Squad.