My brother paid his fees, signed a lease for a mov...

My brother paid his fees, signed a lease for a move in date this month. Made moving arrangements, set up utilities and I booked a flight to go and help him move. After all of that, they called him and told him that he had to change his move in date to next month (no options on another unit, no accommodations offered, no sorry...only "You need to change your date). All because the current residents will not be out on time. Thats not his fault. You offered the move in date and he signed the lease
What? Are you serious? So now the flight i booked can't be used, he has to stay in a city he is unfamiliar with spending money at a hotel until the apartment becomes ready. This is insane, unprofessional and not a good way to do business by breaching a contract after it was signed. You could have at lease offered an accommodation for him or another unit instead of treating him like anyone especially after he already signed the lease. Please contact me if you have any questions