Not that isn't. He raised a lot of good points. Except maybe for nobody willing to keep on the fight. 80 politicians voted against Pétain being granted full power in July 1940.
https://en.wikipedia.org/wiki/The_Vichy_80
Members of the government embarked on the Massilia liner in Bordeaux with the hope of going to algiers and create a free France government thre, but they were caught and emprisoned.
Mandel and Blum are often cited as possible De Gaulle alternative, but there was the issue that were jews and as such, vulnerable to nazi and vichy madness.
A TL with Mandel in De Gaulle shoes would be pretty interesting - although France Fights On probably fit the bill
Sure but the problem is that neither Blum nor Mandel did so.
They did not consider flying to London. They considered going to north Africa and did it in such a slow way that it could but fail the way it failed.
When one decides to rebel against its government, one needs to act swiftly and by surprise.
Other problem is that both Blum and Mandel were jewish and this may have harmed their cause given the antisemitism of Vichy's regime.