While not wanting to get into the argument you seem to often making statements that are known to be wrong. Please not this has nothing to do with the issue of planetary protection, in which you may be completely right for all I know.
You seem to often speak of logical arguments and pointing out logical flaws in people's arguments and then you give all of your evidence in terms of probabilities. you say maybe this, and probably that, and almost certainly, but these terms have nothing to do with logic.
Logic is a structure involved in proving something is right or wrong. For example Boolean algebra is pure logic and can be reduced to yes/no arguments and run computer programs.
By definition as soon as you say anything based on probability you are no longer being logical, indeed logic can be defined as a structure that excludes probabilistic statements. It involves the law of the excluded middle, where all arguments must be black and white with no shades of greys. If you don't believe me read some books on logic.
Probability on the other hand is by nature not logical as it only refers to independant events. By the definition of probability it can never be logical, because logic assumes an outcome depends on the axioms it refers to, while logic assumes an outcome does not depend on the axioms it refers to. Complete opposite things by definition.
When you mix these in an argument you seem to jump from logic to saying therefore probably, and then from probably to therefore logically. I can only assume you are doing this from the heat of the argument but it leaves people having to separate these parts so they can evaluate what you are saying.
This is completely separate from the points you are making, which for the most part are well thought out and motivated by a desire for knowledge. If you use this method of mixing logic and probability you will only end up with things that are not proven when it appears they are. If you don't spot this you will end up frustrated as to why your ideas are not accepted.
I am not going to get into a flame war on this but perhaps you should try to separate logical and probabilistic arguments.