Enough is Too Much?

In Earlene Fowler's latest book, Tumbling Blocks, the protagonist is driving somewhere with her dog. She doesn't roll down the window for the dog to stick his head out, and explains it (it's first person narration) thus:

I'd read enough about dogs' eye injuries from flying debris to do that any longer.

That sentence strikes me as weird. Enough + any longer doesn't work for me in a positive sentence. If it's going to have enough the sentence needs a negative verb. Without the negative verb, any longer needs to be accompanied by too much.

• I'd read enough about dogs' eye injuries from flying debris not to do that any longer.
• I'd read too much about dogs' eye injuries from flying debris to do that any longer.

The sentence is a negative one: she doesn't do it any longer. By itself enough isn't negative - it can work in either sense:

I'd read enough to do it.
I'd read enough not to do it.

But without a negative, any longer just doesn't work, with or without the enough clause:

I'd read enough to do it any longer.
I do it any longer.

That's just not English.