No. For the following 2 reasons.
1. They stopped being the super science guys a long time ago. Now they're the resting on their laurels, assuming they know better than the rest of us, and doing no new research guys.
Just because they stopped the journey for their full potential, doesn´t mean that they aren´t still the super-science guys, as demonstrated by the Fanatic Materialist Ethos.
2. They're not being irrational. They're being distrustful of machine intelligence, which is their default position, for reasons that were presumably perfectly rational a long time ago and may very well be rational now.
Being Distrustful is their default position. It is also their starting posion to not let dangerous knowledge to fall in the hands of those who can´t handle it (which, in their perspective, is EVERYONE ELSE). That isn´t irrational.
But for them to still oppose you even after you have PROVEN, BEYOND DOUBT, that you can handle this knowledge (Synth Ascension, in this case) is indeed irrational.
I mean, if you play anyway close to how I play, you're a major threat to the stability of the galaxy.
In this case, they are going to oppose you for reasons entirely unrelated to the Synth Ascension and AI techs, don´t you think?
Two words: Ben Carson.
You can be brilliant in one field and an utterly ignorant fool in others.
The Keepers of Knowledge are incredibly fearful of an AI revolt- and would be a better springboard than an entire space-empire of uploads in lovely robotic bodies, just begging to be suborned and taken over by a rogue artificial intelligence?
But Ben Carson is ONE example, ONE individual, out of millions. The exception to the rule
What you are proposing is that the Materialist FE is an entire civilization of Ben Carsons.
Which, in hindsight, scares me even more than their Tachyon Lances...
The falacy you did here is confusing rational with pragmatic.
The thing is, even if they dont believe in gods and are calculating, scientific minds, it still doesn't forbid them to be paranoid, neither remove the emotions from equation. Remember they already had a Robot War and have traumatic experience with it. Maybe even their empire has fallen becouse of the AI rebelion. Maybe they even did every precaution to prevent it and they still failed. They also must know that with few hundred races building advaced AI - the possibility of making malicious robots grows with every empire rising.
Absolutely true, But their scientific minds ALSO mean that they will search for evidence, evaluate it, and do their best to decide their course of action according to the facts.
They´ll most certainly watch your neck like a hunting dog, but once they find that there is nothing different about your civilization behavior, they will probably leave you alone.
Also, in the particular example I gave you, the difference between "pragmatic" and "rational" is pretty much non-existant