There is a "buffet" of evidence in the JFK assassination that allows people with various theories to pick and isolate witness statements and impressions that support their case. Some of the theories are quite impressive; the Mason Theory presented an ingenious pathway.
I think that's really well put, a "buffet" of evidence.
What's striking is that it seems possible to pick several differing 'narratives' and have a range of supporting evidence for each.
The lack of any reaction from Landis, Hickey and Ready I don't think is so easily brushed away. Ready says he immediately turned to his "right rear". We don't see this in Zapruder but we do see this in Altgens6. Ready is obviously recalling the moment accurately as we see it confirmed in Altgens6 and I find it difficult to accept that these specially trained SS agents would take two to three seconds to react to an "explosive noise".
But, as you say, there's more to the case than this point. That's just the particular part of the "buffet" I am selecting from.