I am so confused as to how you came to all these conclusions. To me, it seemed pretty clear that he wants to develop things, and to program as his job, rather than run a business.
"without doing much of the kind of work I actually enjoy."
"without doing much of the kind of work I actually enjoy."
Under him The Magazine as a product probably would stagnate like Instapaper did. Then he would have sold it anyway.
And, advisory role usually means a decent chunk of shares too. With what Glenn have in mind, this might be a smart financial step.
Given the success of instapaper and the fact he'll have done fine out of Tumblr, I suspect Marco has no need for that and would rather devote his time and attention (something can be distracting even while taking little actual time) to something he'd be happier doing.