The clue is in the job title - Head of Internal Innovation.
His job isn't to buy stuff - it is to make stuff happen using his own people.
You have two choices:
1. Walk away - he is playing you to learn how to do this internally.
2. Change this into an "enablement" pitch - helping his people to do this themselves.
There is a further point.
The idea of a "main decision maker" is a twentieth century one, based on sales calls. Sales people didn't want to waste their time on a journey to a client and relied on the single decision maker to spread the word internally. In those days it was easier to communicate within the company than outside - now it is the opposite.
In the modern sales process, if he is really keen on your idea, he will be introducing you to other members of the team online, asking them to examine your proposal from their perspective and contribute to the decision.
If you don't get that openness and wider involvement, it is probable that he is either not confident in you, or taking a flyer on something the company hasn't sanctioned and wants to be certain before putting his neck on the line, asking for funding etc.
The answer - open up the decision team - ask for who would deploy, contribute to the decision etc. And do some background research - find other likely team members online and see their capabilities, what they are working on etc.