For a house-warming gift, you should buy them a large bottle of Tums. They will need it when the stress of affording that lifestyle kicks in. Do they know anything about property taxes in Texas?
I'm 100% sure they haven't even sat down and put a budget together and looked at the numbers because if they did, they would know it's not sustainable.
The crazy part is he's a realtor, so he is (presumably) aware of debt to income ratios, etc.