Hope he gets it, but I say...
On pace through 22 then the wheels start falling off. Either 2:21 high or DNF (save yourself for another day if you are not getting it).
The forecast calls for a headwind the last eight miles as the course turns onto Memorial past mile 18. This site has a headwind for 31% of the course - only 6-7 mph though). Thirty-one percent would equate to about eight miles. There are a few times in the last section where you are going South, but it looks like mostly into the wind this year.
The quotes of the day from everyone will be about how hard the last few miles were with the wind.
I do hope he nails it though. Good luck, if you are reading this.
http://findmymarathon.com/weather/houston-marathon-weather.php