I understand that even a single study indicating a connection would immediately be seized on by anti-vaccination activists. (I've even seen them manage to take a study that indicated no connection, copy a graph in that study that indicated no connection, and write an analysis claiming it proved a connection.) Out there in the real world, maybe it's good to suppress any such studies. Maybe.

Well in light of how the modern scientific processes produces a bias against contrary views the activists' seizing on any studies drawing contrary conclusions appears to be rational. To put it another way if the process is strongly biased against studies that reach contrarian conclusions, any study reaching a contrarian conclusion that survives the process is much stronger evidence than a study that reaches the mainstream conclusion.