Doesn't sound like it. It sounds like Meehl is giving an order of magnitude estimate. He is saying that it is his impression that both Morrison & Henkel's paper and his own seemed to have little effect on practice.
Clearly he doesn't think it had exactly zero effect, since it affected him!
assuming 1000 reprints somehow implies there should be a discernible 'impact on research habits' seems like an example of what your referenced Figure 2(o) calls 'Estimating parameters from sample'
"Estimating parameters from sample" (on the right) would be his observation that there was little discernible effect. Thinking that 1000 reprints of the paper would have a larger effect on practice would more correspond to "theory" (on the left), although that is a pretty vague one.
Clearly he doesn't think it had exactly zero effect, since it affected him!