To the OP - You did a good job of documenting what you observed. I really would urge you to send that in an email to the VP's in charge of Cust Service East and West. You might have to dig around a bit to get thier email addresses or the email addresses of thier admns. They should read what you wrote. Both the Managers on duty at IAH and PHL that night should be spoken too in my humble opinion.
Providing misinformation , in my mind, is far worse than no information. Ideally they just should have been honest with the folks in IAH.
45 minutes a person for rebooking is ridiculous. Maybe thier hope was that the others in line would grow tired and just leave.
What was the cause of the delay in the first place? I'm thinking something under the airlines control if they were offering hotel vouchers. BTW - The FA on board probably just repeated what the GA in IAH told her about connections -why I don't know - trusting sole that she apparently was - and gullible.