He wants to kidnap Hinata because plot. i'm not even gonna try to justify it.
The only reason the seal is in there is to let the main house kill branch members if they try to revolt or to not let the Byakugan be stolen. As I heard
"I think it is a broader foreshadowing of when he became hokage he would also marry Hinata"
Neji had just described the system to Naruto. Naruto found it horrible as a normal person and an hero should find. He was talking only about himself.
Stop trying to retcon the plot as foreshadowing for your clearly decided at the last hour pairing!
Don't we notice Hinata's affection for Naruto within the first several chapters?
Hinata becomes a better person because of her relationship to Naruto throughout the Chunin exams.
Naruto then confronts Neji and his ideas of fatalism and then promises to change Hyuuga when he becomes Hokage.
Well how would he do that and why would Kishi make Naruto have this discussion in front of the girl that adores him?!
(There are like a million different ways that conversation could have come up, it is fiction after all...)
When I read the chapter I thought " Oh dang, they're gonna fall in love and Naruto will change Hyuuga with Hinata as a couple." I've had this thought for ten years, so I'm not so sure I'm performing a retcon.
I hate to spoil it for everyone but the NaruHina relationship has been obvious through the whole run, if I have a bias its because Kishimoto clearly displayed one. (I don't really have an odd personal bias that colors my theories, it's fiction dude I just observe it and report what I see.)
Stop trying to retcon my comment as retcon when it's not retcon.