To be fair, this mode is a direct counter to the zero-click attacks that Zerodium is offering the high payouts for. It specifically blocks all the (currently) known attack vectors.
Maybe Zerodium will offer a new tier for a zero-click attack on an iPhone on Lockdown mode in the future.
I wouldn't say that is fair in that very few people can use that mode, so the net security win is minor and there exist hyperlocked down Android versions for years on the open market. A friend of mine even worked on one.
This space is murky at the top end.
The Zerodium payout offering is a rough proxy, but for 99.99% of consumers the security win for a iPhone are mostly about how they don't have to think about the manufacturer (tell your tech illiterate friend to buy an iPhone is easier than saying "Android but only Google or XYZ manufacturer") and how the privacy differential helps out a bit.
Also, plenty of people can't enable crazy hyper secure mode without bleeding information that they've enabled it. So this isn't as helpful as it may seem.
> I wouldn't say that is fair in that very few people can use that mode
Very few people are being targeted by nation-states. But more importantly, these are not a random set of people. These are head of states and companies, free speech activists and journalists, and people with access to top secret information. I suspect that a large set of them are aware that they are potential targets.
Maybe Zerodium will offer a new tier for a zero-click attack on an iPhone on Lockdown mode in the future.