I think that is a little naive. You don't need to look too hard to find examples where it is clear you'd have to go very far before negotiation with government was actually off the table. This isn't about like or dislike, though, which you seem to have read into this yourself, but about a deliberate spatial policy which sees Manchester invested in and Liverpool not. You are partially right that Manchester is skilled in negotiating deals, but this isn't talking about something that one has negotiated and the other hasn't. HS2 was always going to Manchester and never going to Liverpool, it's very basic stuff. Manchester isn't buying into Osborne's agenda, but simply benefiting from being the lucky chosen one and doing all it can to stay that way.
Should the answer come back as "no", as I expect it will, maybe we can carry on the conversation then. In terms of Liverpool council taking on risk, the spending of £2bn of devolved funds on this is already as risky as you could possibly get.