Totally sensible requirement.
TACO Trump has drastically altered tariffs and reneged on deals within this timeframe. Even previous military announcements have been reneged in this time.
The US is unreliable.
It could be 2 weeks, and would likely have the same safety. But a month makes sense.

Only issue I can see is the absolute tension this will cause in oil prices and the stock market (and the new unregulated predictions market aka pure unregulated gambling with 0 actual net productivity).
Imagine a massive bet against "the strait opens" 1 hour before trump declares & enacts further hostilities which breaks any truce and keeps the strait closed.
Cause I'm pretty sure that shit has happened already, insiders know and can make "predictions" with impunity and bank big bucks.

I don't know the particulars of who is right & who is wrong in this.
But Iran have found a big fucking lever they can actually pull, and are using it very wisely. Unlike nukes or projected power, Iran can actually pull this lever whenever they want and absolutely cripple international supply chains from food to microchips.