I don’t know, I can see both sides here. A scissor lift is going to be very unwieldy, getting tiles and concrete and stuff up there. And it will cost more (a cost that will be borne in part by the owner) and likely extend the time of the project.
However, providing blanket access to your entire unit for the works is also a big ask – it does happen every now and then, with owners having to move out. Whale’s suggestions re the conditions you might apply if access is gained internally are good ones.
I think the test the CTTT would apply in a case like this is, what is reasonable?
I am more concerned re ongoingissue’s comments re the contractor as it does sound a bit dodgy and on its face the OC is motivated by cost rather than doing the job properly. Did you put up any alternative contractors to do the job?