I would bench him without even thinking about it. Williams isn't proven enough to start in Houston. There's no telling how many runs he could give up.
Incidentally, his last two starts against Houston, the first time he gave up 5 hits and no runs in 7 innings in Houston, and the second time he gave up 3 runs and 6 hits in only 4.2 innings, at home. However, he had a couple of starts last year and the year before where he just blew up completely. He could pitch great tomorrow, or he could be terrible.