It's certainly a "statement of policy" - it is Labour's policy. It is/was in the Labour manifesto 2024 and this is not the first time Starmer or indeed any Labour representative has said that or something along those lines.
Labour manifesto 2024:
- Strong foundations: "[new Border Security Command] will be funded by ending the wasteful Migration and Economic Development partnership with Rwanda."
- Labour's fiscal plan: "scrap the Rwanda scheme" (in context of above)
Guardian newspaper, May 2024:
Labour will not allow any deportation flights to take off for Rwanda from the moment it wins an election, Keir Starmer has said.
After a speech in which he announced his plans to tackle illegal immigration, Starmer committed to scrapping the Rwanda scheme “absolutely, flights and all”.
Starmer told Sky News: “There will be no flights scheduled or taking off after the general election if Labour wins that general election.”
And a number of occasions beforehand, going back to at least October 2023. Daily Telegraph:
Sir Keir Starmer has declared that he would scrap the Rwanda border plan even if it succeeded in slashing small boat arrivals.
Whether it's a "statement of fact" seems like a question of time and whether it's a "prediction" seems a question of semantics: it is something they intend and if things go as they wish then it will happen.