Having a transfer strategy is important, but there are a few players that are worth moving heaven and earth to sign if you get the opportunity. Kane is one of those because he is as close to a sure thing as it is possible to sign. I see it as analogous to when Fergie signed Van Persie.
Hojlund has been bought for the future - expecting him to fire a team to a league title or a CL any time soon is unrealistic, and a huge amount of pressure to place on young shoulders. I remember the days when we had Cole, Yorke, Solskjaer and Sheringham, or when we had Rooney, Ronaldo and Tevez and Fergie still went and signed Berbatov. I do think we still desperately need another centre-forward, we can't rely on Martial which means we are a single injury away from another Wout Weghorst situation.
Your view is absolutely reasonable, but it's ridiculous to describe people that would like to sign Kane now as idiotic. I'm absolutely certain Fergie would do everything in his power to sign Kane now if he was still in charge.