Could have just been a chance for key staff to make contact in advance of work which will be done when the new Ministerial team is in place and the new government has decided what its policy is with regard to Universal's proposal. I'd guess they would have wanted to discuss a series of "what ifs", procedures for things like consulting on Universal's application and environmental statement, that kind of thing. I have no inside knowledge of this, but I'd be amazed if any Labour Party representative had expressed anything more than a general welcome of the potential investment, they certainly won't have committed to any particular plan not least because they are not allowed to instruct the Civil Service on anything they might wish to do if they form the next government. Also the Ministerial team(s) that may be responsible for approving the way forward and determining the outcome of the planning application won't yet be known, perhaps even by Keir Starmer in respect of the junior ministers in the two relevant departments (which themselves might change after the election).
If you want to get in to the detail of this, you can see the
General Election2024 Guidance for the Civil Service. Note in particular Section J1, which prohibits a new public consultation being launched during the election period. From what I can see, this is the essential next step in the planning process and without that consultation taking place approval for Universal's plans can't be given. But it's worth remembering, the election period is only 6 weeks (although it's beginning to feel a lot longer than that!), so we don't have to be patient for very long as a result of an election being called a bit earlier than most expected.