No - the rules around Sectional Completion are the same as Completion Date i.e. only agreed acceleration can ever bring forward a sectional Completion Date and an implemented compensation event move it later. It is only a Key Date that can be instructed earlier and then assessed as a compensation event.
For what it is worth, I don't think the contract should allow this, I think Key Dates should be treated the same way as Completion that it can only be brought forward by agreed acceleration but that is not what the contract says. The risk to the Contractor is that it will be agreed at a lower value than the Contractor agrees and then only senior representatives (under NEC4) or adjudication can then over turn that.
For what it is worth, I don't think the contract should allow this, I think Key Dates should be treated the same way as Completion that it can only be brought forward by agreed acceleration but that is not what the contract says. The risk to the Contractor is that it will be agreed at a lower value than the Contractor agrees and then only senior representatives (under NEC4) or adjudication can then over turn that.