This treason argument hasn't a leg to stand on.
We're talking about a parlementarian regime there, with a huge cabinet instability.
While, it's worth mentioning, France is still deep in Algerian War and Mollet under huge pressure on it (being one of the reason of his governement being dissolved)
Giving that Mollet had stritcly no power or legitimity to undergo such negociations (for the record, he first asked a dominion-like status, then Commonwealth), that were strictly personal and secret, the very moment he proposes that, his government..."implodes" doesn't covers it...the government "big bangs".
He's lucky if he escapes a trial by the Parliment on these grounds (before saying it doesn't have a leg, I suggest strongly to take a look on law about it).
Article 56-57 said:
Les ministres sont pénalement responsables des crimes et délits commis dans l'exercice de leurs fonctions.
Ministers are penally responsible of crimes and offences commited as they erxerce their functions.
---
Ministers can be accused by the National Assembly and send on trial on the High Court of Justice
The National Assembly statues on a secret votes and to the absolute majority of its members, at the exception of who'd participe to trial, instruction and verdict.
Penal Code said:
Le fait de livrer à une puissance étrangère, à une organisation étrangère ou sous contrôle étranger ou à leurs agents soit des troupes appartenant aux forces armées françaises, soit tout ou partie du territoire national est puni de la détention criminelle à perpétuité et de 750 000 euros d'amende.
Surrender to a foreign power, to a foreign organisation or under foreign control or their agents either troops of french armed forces either all or part of national territory is punished by perpetual detention and [fine, I don't managed to find the ammount in ancient francs]
---
Maintaining intelligence with a foreign power, with a foreign entreprise or organisation or under foreign control or with their agents, when it's susceptible to harm the fudamental interests of the nation, is punished of ten years of detention and [fine]
And I didn't put all the relevant articles, believe me, there's enough grounds for a trial. I don't think it would result on a full punishment if at all, but Mollet clearly went trough negociations without the legitimacy to do it, and that's gonna backfire hugely.