T-symmetry (string theory) for minimum length?

[nomadreid]

If I understand Brian Greene’s argument (in The Elegant Universe, and repeated elsewhere) for the Planck length being the minimum measurable length based on T-symmetry in string theory, it goes something like this:
There are two ways to measure things, one with vibrational energy v and one with winding energy w. Measurements with v gives one set of results; measuring with w gives another. The two sets of results can be seen to be isomorphic by the identification of the lengths with their reciprocals. The two give the same results at the Planck distance. Therefore (?) when a length is measured with probes, above the Planck distance the probe measures with v, and below that distance, the probe measures with w. Hence one never obtains a measurement less than the Planck distance.
If this is a fair summary, could someone clear up that inference marked with a question mark? If it is an incorrect summary, what have I missed?
Thanks.

 

[Demystifier]

This may help: https://arxiv.org/abs/hep-th/0605250

 

[nomadreid]

Thanks, Demystifier. Downloaded.