The last sentence should be definitive for you because Jason states: “Whether the game is freely accessible or not…” meaning that both closed and open tests are allowed.
The last sentence is quite clear … it says it can be freely accessible (open) or not (closed)
I am not sure that there is anything else I can say at this point.
The advise I would give to any author unclear of their “beta testing” is to contact customer support, and your inquiry will be routed to the appropriate person (most likely Jason).