Does savings lead to investment in physical capital?
I think that part of the blog post is just saying that savings may not equal investment in capital immediately, because there can be a delay caused by firms accumulating inventory.  But firms can't continue to accumulate inventory indefinitely, so this is only a transient phenomenon.  Sooner or later, inventory will reach a new equilibrium and savings will equal capital investment again.

He then goes on to talk about the reasons that a higher savings rate is unlikely to be sustained (the paradox of thrift).