Can't agree with that statement, and the real world tends to back me up.
Take the BAe146 for example....no thrust reversers fitted, but it has spoilers (and an airbrake too).
Many aircraft types have no reversers but do have spoilers.
I would have thought that choosing between the complexity and weight of a reverse thrust system - when compared to a spoiler system - would be a no brainer.
The advantage with the TR/brake only combo is that the two decel devices are somewhat independent. Spoilers are pretty useless without brakes. I guess I meant to say that if I was only allowed ONE, it sure wouldn't be spoilers.