It actually seems like the restriction of access is due to defects in the rollout. That is, a combination of bugs (issues with access that was expected to have been available), an apparent failure to adequately recognize that there was an immediate need for broader access on first rollout, and IMHO a failure to provide adequate description of what the intended behavior after rollout would be to the folks who needed it.
If you look at what @MichaelaMonson posted in the BSA announcement thread, there’s clear indication that the rollout has not gone as planned, and that broader access is intended. That’s supported by various posts by @edavignon and other members of the SUAC.
It’s no secret that I’m not a fan of this change, but it does not appear to be an attempt to restrict access, per se. More an, IMHO mishandled, attempt to provide a new release of the functionality on the codebase/platform the BSA appears to have anointed as the long-term replacement for Scoutbook.