In the article 4.1.2c of the constitution (v4.1) it is explained that a role holding a domain must allow access to the domain upon request, if the role sees no objection.
The constitution doesn't specify what could by defined as an objection in those cases, but my guts tell me that those objections need to be tested on their validity, exactly like in a governance meeting. I have experienced situation where objections are needlessly predictive or the objection is already a problem and would not be caused by granting access. Withholding permission in such cases doesn't seem healthy.
Very simple example - The omnipresent Website domain:
Role Communication hast control over the domain: Website content. Role Outreach would like to add content to the website to market a new service. Role Communication objects, due to the fact that the website is overloaded and also a new website will be launched soon (no time estimate) and the new content rather needs to be added there.