This looks like a serious case of fancy play syndrome on both sides.
So I was wondering about that. The game did kind of morph into something I wasn't expecting.
I don't think Develop and Upgrade are enough to support buying any Rats at all. I want either Moneylender or Spice Merchant (Spice Merchant is normally better, but here the buying power of Moneylender could be useful as you want Gold to rush a Province) and one Upgrade.
That's kind of a relief to hear; my plan on 4/3 was to go Moneylender/Silver with that basic idea in mind. On 5/2, well, I get my Upgrade, but as you note...
On the 5/2 you don't want the Moat: you trash it the second time you draw it and could have killed a Copper instead.
So I debated Moat a long time. It was the only draw on the board and I wasn't completely sure where this was going. And I knew I could just Upgrade it...but, yeah; that's a two card swing in deck size right there.
I'm not entirely convinced by Workshop either. The only interesting targets are Tournament and Island. Grabbing Tournaments worked out here because Rabid couldn't block them, but normally you'd end up with too many, and you don't want Islands because the trashing is great and you want the Provinces in your deck.
Fair enough. I have to say, I became convinced early on this was going to three-pile and then played on that basis. But I still needed to get lucky with Followers to make it happen.