[quote from article] "... In response, the body increases production of 1,25-D from 25-D, leading to one of the hallmarks of chronic inflammatory disease: a low 25-D and a high 1,25-D." [end quote]
Another way to look at this is that since 25 D is the raw material needed to produce 1.25 D, the low levels of 25 D could just as well be cause by the body using up all the stores to produce the high levels of 1.25 D.
In this case, additional 25 D would allow the bodies immune system the raw product needed to fight the inflammation.