Some elements of the technique to consider.
Delayed Sword's attack is a right hand grab to the lapel, with, possibly, a follow up left punch, right?
If so, is economy of motion necessary? If a person grabs you there is no reason to respond until you determine the threat. No punch, then you have all the time in the world to deliver a hammering block (strike). This is a Significant Initial Response, which will, if delivered properly, more than likely drop the attack to his knees. (Depending on target... bicep or shoulder joint, which both correspond to nerve meridians)
If there is a punch, a "circular" block with the right hand should help catch the attackers left punching hand. Of course, the stepping back into a right neutral bow should check the attackers width and assist in negating the punch, but if you cannot step back, the block should catch the punch.
I agree with KenpoDoc here. The block is less effective if delivered from point of origin for reasons you stated and, I believe, my above rational.
Should inward blocks always contain circular motion to allow the forearm to become a striking rather than glancing force?
Depends on the size of the circle. From my experience, as I get better, my circles get smaller and stronger. In the beginning the inward block has a sharp edge circular movement. Akin to writing in big, bold, print. As I have improved and the muscles (brain) have had a chance to "memorize" the movement, the hard edged circle becomes smoother and smaller, but maintain the same structural integrity.
Doc's inward block has evolved to the point where he is "writing in very tiny, rounded, cursive." The circles are intangible, but exist. The muscles and brain have been hardwired to the point where thinking about the movement is enough. If you don't believe it, have him come do a seminar! Ouch...
I realize this fly's in the face of what traditional Kenpo does. Even the hammering inward block is done differently. We don't have a "point of origin" block per se.
This is all very hard to explain without physical examples or ways in which you can test it yourself. Perhaps we can devise a description of how to test an "indexed" (which is the term for it) inward block. Dr. Dave? Have the time?