"There's no problem getting access to the manuscripts to read them, and many people have - they just can't publish them."

Could you be a bit more forthcoming? If they haven't been published, how is there 'no problem getting access to them'? Are these manuscripts online for instance? What's the name of this American academic? Have you read these manuscripts? Do you have to book an appointment and go to the guy's house?

Likewise, when you say, "Given Clare's chaotic life, nobody selected stuff for publication in the usual way", I'm again not entirely sure what you mean: are you referring to how Clare's poems were published during his lifetime, or after?

If the former, then that's well documented). If the latter, well, I'm aware of several different editions and they've elected to compile his poems either chronologically or thematically, neither of which are unusual in editions of selected or collected poems.