Trademarks are bound to markets / domains (toys vs computer perception). In my limited understanding, nerf the toys and nerf the computer perception tech, do not serve the same market.
That's not universally true. For most marks, you are right. But for certain particularly "famous" marks, the owner has a potential cause of action for dilution of the owner's mark. Unlike trademark infringement, which requires a showing of likelihood of confusion (which is bolstered by a showing that the two purported mark users serve the same market), trademark dilution does not.