Hey gang! Aren't all these politicians silly? A buncha kids, that's what they are! Not like us, we're grown ups - aren't we, kids? This is the Green Party's pitch, in toto:
Anyone with a long enough memory can place the inspiration for this vomit-worthy atrocity more or less precisely. It's Liberal-SDP, circa 1987. The idea is to set up two untenable extremes, then define an imaginary, common-sense, middle-ground voter to cater to. But this is not just condescending, trivialising tripe, it is politically unintelligent.
The problem for the Greens, as they know very well but can't admit here, is that they agree with most of what Corbyn is doing. And for as long as Corbynism is on the ascent, and actually achieving something, they are going to have trouble defending their hard-won electoral niche. The smart play, and the genuinely adult thing to do, would be to declare this openly: "We agree with Jeremy when he opposes cuts, works against Trident, and denounces racism and war. The problem is that he's the captive of a party whose elite despises him, won't let him be effective and will one day try to get rid of him. We will work to support Jeremy in parliament when he does the right thing, but if you want to see a progressive politics free of these sorts of games, then vote for the Green Party." That wouldn't stop them losing votes, but it would give them somewhere plausible to start from in the event that Corbynism does begin to degenerate.
The fact that the Greens can't openly admit that on most policy specifics, they agree with Corbyn, is itself the most infantile, tribal, yah-boo tedium, packaged as an appeal to #grownuppolitics. If the Greens want to openly become the new Liberal Democrats, that is their prerogative - but I don't see the electoral yield in that.