No, it is not only open source but a healthy mailing list with a lot of interested parties.
> lead by Blockstream
No, Poon and Dryja are not employed by the company Blockstream. The latter seems to be more focused on their sidechain solutions.
> the work is even patent-encumbered
No, there is nothing to suggest this. Patents have to be public at some point.
No, it is not only open source but a healthy mailing list with a lot of interested parties.
> lead by Blockstream
No, Poon and Dryja are not employed by the company Blockstream. The latter seems to be more focused on their sidechain solutions.
> the work is even patent-encumbered
No, there is nothing to suggest this. Patents have to be public at some point.