Nuclear SSTO a really bad idea?

Looks like what I considered a brainstorm has already been considered and rejected.  Kirk Sorensen, the guy who wants to build molten-salt reactors, worked on a similar project years ago.  His thoughts on the subject is on the blog Selenian Boondocks.  Basically, his objection is the poor thrust to mass ratio of nuclear thermal rockets.  They are too heavy.

Some bad mouthing for James Dewar's book came from Trent Waddington ( QuantumQ).  Too late to cancel the book order.  He says it's a bad read.  Yikes.

I still like the idea of a nuclear thermal taking off on a runway, though.

Update:

It should be noted that James Dewar didn't advocate an SSTO.  His idea was for something akin to an upper stage.

There's a doc file that piqued my interest.  I got it from Dr. Space's website in connection with having Dewar on his Space Show broadcast.  The link can be obtained there.

It's an interesting read.  I have to say, after reading it, that even Dewar may be underestimating the potential of these rockets.