I understand where you are coming from, although I would look at it from a different angle:
The integrative decision-making process (IDM) which is the process used in a Governance meeting, is set out to guide the proposer from tension to an accepted proposal. It is 100% the proposer's responsibility to solve his tension as it is 100% everyone else's responsibility to solve their respective tensions.
Holacracy is enabling role-fillers to come up with incremental changes that are "good enough to try" and therefore adapting Governance on a continuous basis.
So although IDM gives the proposer the opportunity to integrate feedback to make the proposal "better" he has no obligation to do so whatsoever.
So if people are not responding to asynchronous Governance proposals, this only shows me that they have different priorities but are not harming the organisation in any sense. The proposer's proposal should already be good enough otherwise he probably would not have circulated it. If a week later other's feel a tension to change Governance to the better, there is no one stopping them from processing a proposal via the Governance process.