Yes, the current speculations in this field are of wildly varying quality. The argument about convergent evolution is sound.
Minor quibble about convergent evolution which doesn't change the conclusion much about there being other intelligent systems out there.
All organisms on Earth share some common points (though there might be shadow biospheres), like similar environmental conditions (a rocky planet with a moon, a certain span of temperatures, etc.), a certain biochemical basis (proteins, nucleic acids, water as a solvent, etc.). I'd distinguish convergent evolution within the same system of life on the one hand, and convergent evolution in different systems of life on the other. We have observed the first, and they both likely overlap, but some traits may not be as universal as we'd be lead to think.
For instance, eyes may be pretty useful here, but deep in the oceans of a world like Europa, provided life is possible there, they might not (an instance of the environment conditioning what is likely to evolve).
Why do we imagine our actions could have consequences for more than a few million years into the future?
Unless what we believe about evolution is wrong, or UFAI is unlikely, or we are very very lucky, we should assume there are already a large number of unfriendly AIs in the universe, and probably in our galaxy; and that they will assimilate us within a few million years.
Therefore, justifications for harming people on Earth today in the name of protecting the entire universe over all time from UFAI in the future, like this one, should not be done. Our default assumption should be that the offspring of Earth will at best have a short happy life.
ADDED: If you observe, as many have, that Earth has not yet been assimilated, you can draw one of these conclusions:
Surely, for a Bayesian, the more reasonable conclusion is number 2! Conclusion 1 has priors we can estimate numerically. Conclusion 2 has priors we know very little about.
To say, "I am so confident in my beliefs about what a superintelligent AI will do, that I consider it more likely that I live on an astronomically lucky planet, than that those beliefs are wrong", is something I might come up with if asked to draw a caricature of irrationality.