"Essentially, the arithmetic did not make sense as Labour and the SNP already had a majority"
The Greens weren't needed for a majority. The notion was for a broader coalition - perhaps a bigger talent pool.
"I don't really see how you can be annoyed with the Green group for something that has come out of internal wrangling in the SNP group."
Nope. Just speculating that (now) a Green might have been a good alternative to/replacement for JO - in the context of the 'assumption' (which might be wrong) that CEC's SNP group doesn't have anyone interested in 'active travel'.
"just imagine the sniping and obstruction a Green vice-convener would have had to put up with!"
Er no. In the alternative universe the Greens would be part of the Coalition not a sub-set of the SNP.
I think the Greens should have joined the coalition. I said so at the time. They chose not to. I fully accept that I was not part of (or party to) the (inevitably difficult) negotiations.
They made a political decision at the time which I presume they don't regret.
As is moderately well known, I am not a member of any political party (and never have been).
In general I would like to see more Greens and others from small parties - like the 1999 Scottish Parliament. I believe it's generally accepted that Green influence at Holyrood was reduced when Patrick Harvie tried too hard to get concessions from John Swinney.
I believe at CEC the Greens have less influence (some power even) than they might have done.
That's all.