I see but the problems you mentioned here in terms of the spending that is rather limited, it could also have to do with the potential change in ownership and that might keep the Glazers from opening their wallet and allowing a lot of costly transfers. I don't know what the situation is right now and whether that ownership change will happen, but in regards to planning the future this could turn out to be an issue if those negotiations take place right when the transfer window is still open and it is unclear which way the club will go in the future.
Manchester United must have prepared an option when De Gea left it doesn't make sense if they go through this season only rely on 2 goalkeepers Dean Henderson and Tom Heaton (injury). The latest news, Manchester United is negotiating to bring young goalkeepers from Japan he is Zion Suzuki (20 years) Manchester United has sent €5 million offer to Urawa Red Diamonds, this is the highest offer from Man United to the players who have been brought from Japan League. Several sources reported that the agreement was approaching the final stage.
Besides that Andre Onana, Inter Milan goalkeeper is also still in negotiations, Manchester provides a budget of around 42 million to bring in Andre Onana. Although this offer was rejected, the fact was Inter was looking for another goalkeeper which means Manchester has a chance. The possibility of transfer continues to increase to 71% based on Transfermarkt.com
If Andre Onana comes that is a different story, but Manchester United is not all set if they start into the new season with only young goalkeepers. I guess that is why they stl keep the option with De Gea as some kind of joker. But De Gea won't play that game for very long and I assume he will make Manchester United bleed hard financially if they have to decide and offer him another new contract. He won't sign a contract below his expectations.