I don't buy the line that we should keep our cards close to our chest. Brexit is not like haggling on ebay over Wombles memorabilia.
There are 2 essential components to our approach to Brexit. One is the cost of various options to us. This is essentially common knowledge
Hammond and others have said that these things have to be private, but a few economists in Brussels can do as good a job as those in HMT.
The other component is how we are prepared to trade-off eg freedom of movement versus single market access.
It's not right that that should be chosen by the government at all, let alone chosen in private.
And the referendum did not give a steer on how these things should be traded off in the light of multiple Leave positions on it.
The real reason for the silence is the difficulty the factions in the Tory Party are having taking a view on the trade-off.
Conjecture to that those described as 'away with the fairies' don't accept common sense estimates of the costs of different options either.