The main reason I disagree with trying to preach to the Caldari is that it flies in the face of a lot of PF, and makes little sense given the highly controlled nature of Caldari corporate society.
1.) Caldari are cultural purists. This is their "thing". Why in the world would they want other cultural influences, up to and including their allies? They fought a war over that kinda thing. After all, the Gallente used to be their allies too.
From Caldari: Demographics
The corporations emphasize this in their enculturation process, enforcing a single Caldari culture and identity for the purposes of unity and cohesion.
The megacorps actively and methodically go to great lengths to insure cultural homogeneity. Allowing a preacher from another culture hoping to break that homogeneity would literally make no sense. Literally, one reason many Caldari players are reacting so poorly to this is that it directly contradicts the stated goals of the State itself, and therefor their characters' goals as well.
2.) According to PF, Caldari corporate citizens are highly indoctrinated, and megacorporation control and Caldari enculturation is strictly monitored and enforced.
Again, from Caldari:demographics
Where corporate control is weak and/or threatened by non-Caldari influences (such as colonial outposts in remote areas or space stations on major spacelanes), citizens are frequently rotated between locations, resulting in very few permanent residents in these places.
Certainly, a preacher seeking to spread another religion, i.e. a non-Caldari influence, would certainly mean that the megacorps would rotate and isolate their citizens away from such things. Otherwise, none of the above statements make any sense.
How would you seek to limit non-Caldari influences, actively and aggressive seek to maintain a singular Caldari culture and identity, but allow foreign missionaries and preachers access to your population? You cant really. Hence, people having a problem with this storyline.