Yeah, when a brokered load involves a trailer drop, from experience, I'd be asking a lot of questions. And if I were a carrier, depending on the way it's laid out, I might ask for something in writing. Like in your case, ask to put in the ratecon a penalty paid to you if it's over 48 hours, or over whatever number of hours, since that's all they're saying they want it for.
One time a broker said "you can drop your trailer at the shipper if you want" on a load they were also very paranoid about if I'd make the pickup appointment (not window) on time. Turned out, winds ramped up to 60 mph while I was deadheading to the pickup, so I pulled into a truck stop, went into the sleeper for a split with the truck rocking in the wind, and based on the forecast of when the wind would die down, gave the broker a new ETA with me waking up at like 0200 when I had been starting my days near noon for a while. So I ####ed with my sleep because the broker wanted me there ASAP and was all "I'll see if they'll still take you with the delay but I don't know."
I got to the shipper. It's a poultry plant. My load isn't ready. I ask the shipper if they have a rough idea of the timeframe. "I don't know. Today's killing day, and the live chickens haven't made it here yet." The broker was pestering me about getting there the night BEFORE the day my load could possibly have been ready!
I had a load like that once. A poultry plant. Empty pallets that paid real good. 24 hr. Drop. They took 23 hrs to unload. I was very worried, but it worked out. So I did another one. Second time, I was in and out in one hour. Lol. You never know. Sometimes best to stay quiet, till needed. They should pay detention by the hour after the 24 or 48hr window.