The criticism isn't entirely without foundation, but it sure makes me cringe. The point that really gets under my skin is the discussion of how the service will be too expensive for the "Average Joe" to use. All I can say there is that if Texas were looking to toss money into the service (say, picking up half the tab) this probably would be something that could be worked around. They aren't. It isn't. There's no realistic proposal that deals with these concerns, so the best you can really hope for is some sort of deep discount advance ticket arrangement (which is something I can see happening, to be fair; the other thing I could see is some sort of Oui Go-type service being run as well (in so many words, think of a world where NJT is running commuter bullet trains and you're on the right track).
For what it is worth, if you in effect take 50% of the total frequent business traveler market (25k traveling 3x weekly; I assume that most of the remainder would be driving with perhaps 10% still flying...this isn't too far off the NYP-WAS situation) 50 weeks per year you'd be looking at 7.5m one-way trips. I'm sorry, that's either pulling a ton of cars off the road (20,500 one-way trips per day) or knocking out a huge number of flights (assuming 200 seats per flight between the two that's something like 100 flights per day). That's a lot of congestion you've just alleviated, either at the airport or on the highways (or on some mix of both). I think there's a clear public policy pro for this project even if your "man on the street" never takes the train.
Some of the point about possibly taking up a future Metro corridor in Houston does seem to hold some merit...but that bit seems like it would reasonably come down to proffers and development conditions. I'd need to look at the maps a lot more closely to see how much space is actually there (i.e. could you pack a four-track line in there? WMATA made it work on the ex-B&O: On one end of the red line, the inner tracks are WMATA and the outer tracks freight; on the other end, the two lines operate next to one another). All Houston would need to do is negotiate access rights for parallel tracks along the route as part of any zoning permissions (and I can't exactly see Texas Central fighting them tooth and nail on that...the two services cooperating would give Texas Central a feeder line and increase any TOD prospects they'd be shooting for).