The ten second thing just means it will be disabling itself a lot. Unless it's just giving you false alarms constantly and then doing a little "my bad, nevermind" beep that tells you it has cancelled the heads up saying you have to take over 10 seconds from now. Which sounds not so great.
Ten seconds is an eternity, so if it sees the tiniest possibility ahead that things will get complicated, it will have to be conservative and give the ten second warning. And when it does get into heavy traffic, it will be disabled.
Because it will be disabling itself a lot (or super annoying if it's giving false alarms) it will either be not in use except on very sparse roadways, or it won't even matter because it will be completely turned off by the driver.
Bottom line, it's a marketing gimmick.
The alternative is a system that goes into the thick of traffic, still active, still helping, still adding an additional level of safety over and above what the driver maintains, but since the system is going into the thick of traffic in an enabled state, actively engaged, and things are dicey, the human still needs to be involved as an active participant in oversight. Ready to take over at a moment's notice. Not ten seconds from now. In this approach, the safety benefits are real, not just marketing. But the human needs to step up and stay responsible and own the shit that happens.