You are failing to take into account the uniqueness of this season and cap implications, making approximately only ten teams in a reasonable financial position to take on his contract. Subtract the teams that already have their QB in place, or have a high enough draft pick to be better served drafting a QB, and that cuts the pool of teams bidding for his services even more.
You also need to factor in the fact Watson is not on a rookie contract, and has a no trade clause. Every time you lower the number of bidders for his services, you potentially lower his value.
You seem to be missing the point. All first round picks do not have the same value. a number 3-7 overall pick has a lot more value than a number 20-28 pick. If you think that the Texans would not take that into account when considering a trade offer, and speculate where the 2022 or 2023 number 1 pick they might acquire from a trade partner might fall, then your are a fool.
two top 10 first round picks > 3 mid round number one picks.
game/set/match