Is the sentence logical?

[sula54]

Dear all,

Please have a look of this sentence.

“However, the birdhouse should not be beyond the reach of any available ladder, for cats or snakes might climb onto it.”

Is the sentence logical?
I think if the birdhouse is beyond the reach of any available ladder and then cats or snakes will not have the chance to climb onto it, but if the birdhouse is not beyond the reach of any available ladder, then cats or snakes will have the chance to do so. I think the original sentence is asking us “not to give the chance to cats and snakes”, so it should be “the birdhouse should be beyond the reach…..” Am I right?

Thanks in advance.

[Tdol]

I think it's logical- there shouldn't be a ladder there, but you should be able to climb up a ladder to get your cat back if it's sily enough to climb up there itself. The animal would climb the tree, not the ladder, and then need help.