I don't think this is true. At least, I don't think their reasoning is solid. For starters, there are tons of ways they could configure show buildings to accomodate these restrictions (i.e the lower right corner of the Simba lot. Secondly, we've already seen from the Disneyland Forward proposed layout that Disney has no problem having the showbuildings abute the hotels (so yes, that is the only way you could do it). Third, assuming that "Property Line" refers to Walnut Street, the graphic seems to indicate that you can get up to 140 feet quite close to the property line.
Edit: From WDWMagic
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