A fined tuned argument.....Heywood style.

[Angrboda]

That's bullshit. Besides which, if you don't have any way of determining probabilities, my first argument (here) that you are either a) making an argument from ignorance, or b) arguing on the basis of the most plausible hypothesis with a hypothesis whose plausibility is unknown, holds, and your argument fails, as neither argument can be successfully completed ('a' is fallacious, and 'b' argued using the principle of indifference yields no winner, even if accepted as an argument). [In arguing to the most plausible hypothesis, if there is no "most plausible" hypothesis, the entire argument fails as there is no reason to prefer one hypothesis to the other. If you say that there is a reason to prefer one hypothesis to the other, you've abandoned the principle of indifference. Either way, you lose.]

Besides, you gave four possibilities, so the odds of a designer are 25%, not 50%.

We started with 4 possibilities and found objective reasons to dismiss 2 of them.

The extreme fine tuning of the cosmological constant allows me to dismiss D. ... As Leonard Susskind put it, "Its too much of a stretch".

This is an argument from incredulity, not an objective reason.

I dimiss C on the grounds as there is no reason to believe this since many coherent models of the universe can be made given our current understanding of physics. Further cutting edge physics...like string theory continue to suggest the possibility the universe could have been different.

This objection doesn't even make sense. "Scientists can imagine things differently therefore they aren't the way they are by necessity?" This doesn't follow and is simply a statement that scientists don't know at present whether this can be ruled out. The possibility isn't excluded on objective grounds.

That left us two remaining possibilities to consider.

You have four possibilities under the principle of indifference. The probability is 25%.

Your claim that this is an argument from ignorance is rubbish. An argument from ignorance is made when a proposition is said to be true because it hasn't been proven false.

An argument from ignorance is also made when you claim, "Not X, therefore Y." It's just another form of the argument. And I didn't claim you were making an argument from ignorance, what I said was that you had two avenues to proceed from, one of which was the argument from ignorance, the other an argument to the most likely hypothesis. Since both fail, it doesn't matter which you took.