Exactly, it's hardly fair to discount Nick not knowing that Harry would do what nobody has ever done before and corrupt the shadow of a fallen angel instead of the other way around.
You need to remember that Nick doesn't really go for a single objective. He's smarter then that. Instead he has a 'main objective', a 'good enough' and a/several 'bonus points'
Nicks plan was to target Marcone because he was vulnerable, but also important enough that he knew Mab would need to respond. So:
In the unlikely even that Mab doesn't get Harry involved in this mess, Nick still gets Marcone (small win, but he'll take it)
In the far more probable event that Harry gets dragged in, Ivy will get pulled along as a Neutral Arbiter and he can grab her (His actual Goal)
And ff possible, he can drag Harry onto his side (His Bonus Goal)
Things only went wrong for him because:
A) He got greedy and overextended when Harry threw Fid on the table.
B) He didn't expect that Harry would have found a way around his safety net by turning Lash on her Creator (and subsequently dying).
To Compare, look at Skin Game:
Nicks 'Small Win' was to grab the Grail (Which he did)
His 'Big Win' was the other Artifacts (Which he missed on)
And his Bonus objectives were Harry Dying and Destroying the Swords.