That's a fair point. The household limits are easy for bots to get around (not going to go into how), but the zip code is more difficult.
As far as the volume and margin on knives not attracting attention of bot users, I disagree a bit there. If someone already had a bought set up for purchasing game consoles, shoes, PC parts... It would be rather easy to add some knife websites to the list. I don't think knife reselling would be their main goal... Just reselling in general. Whatever they can get their hands on with high margins. I also wouldn't expect them to purchase 10 copies of the same knife (which would likely draw attention to them and cause their order to be cancelled), but instead just pick up one or two of each knife that is in demand.
Things like the PS5 and whatnot are only released once every few years and in very, very high numbers, so it makes sense to try to purchase 10+ of them to resell. Knives are a bit different. They may not be released in such large numbers or on such high volume sites, but there are a ton of releases each year. I mean we have Spyderco exclusives, Spyderco sprints, Kershaw exclusives, Buck of the Months, Great Eastern Cutlery, Northwoods... The list goes on and on. If you add the profits of getting even one of each release (or even every other release) it adds up real quick to a big pile of money. Especially if you're also using the bots on game consoles, PC components, shoes, etc... The knife sales would just be gravy for very little extra work.