The reason I find that specific reasoning off-kilter, is because you are assuming the reason that they don't use it because it contradicts other evidence - while in reality - the new evidence (the dating methods which find 4.5 billion years) contradicted them - the evidence which is shown to be most reliable, the least deviational, etc. my point here is that there other sources for why, this is speaking generally here, those sorts of data methods aren't valid. Its not because they contradict the 4.5 billion dating method, but because the 4.5 billion dating method contradicts it, as well as general veracity and lack of reliability.
Of course scientists don't use the other dating methods if they have a bias. Why would they? To say that the new evidence contradicted previous measures is a bit rich and biased. It is not contradiction to show that something is much older than previously thought. But it would be a contradiction to demonstrate that something was much younger than previously thought.
Scientists might at times use the word "contradict" but that is not really what they mean. You see it is ok if a scientist with older tools finds a date which is millions of years in the first place. You cannot measure something if it is billions of years if your measuring tool only goes to millions. Yet, once the tools are manufactured which goes to billion - then the millions of years are obviously obsolete. But the point is the trajectory is one that is always expanding. It won't be long before the current dates become obsolete because newer technology will have found ways to provide greater evidence that everything is so much older than we believe at the moment.
This is why it is not really contradictory when the newer evidence contradicts the older methodology. Yet, if a scientist came along and used new tools to prove the earth was young, it would be thrown out - despite the accuracy of the evidence. Why - it contradicts the bias. Not the science. It would be ridiculed - and not because of the science or the methodology or any thing scientific. It would be ridiculed simply because it is in line with the correct bias. This is what I mean when science is our friend but bias is not.
You see, despite the rhetoric of scientists saying that they seek the truth, they don't. Not unless it already fits within the mainstream of perceived bias. My favorite subject at school was science. I loved science and I still do. I loved math - which is why I studied economics as well as laws and a whole range of other things. Yet, statistics and math are tools that scientists love to use - despite all of their assumptions being demonstrably unsound.
Scientists are also intensely proud beings. They hate being ridiculed. Depending upon where they work, they don't want to lose tenure. Or funding - so they use their knowledge to assist their lords and masters - whether public like the UN or private like their multi-national corps. But the scientific peer system is also extremely cruel. If it does not like your new evidence - you will be cast out - ridiculed, called a pseudo-scientist, extremist, or doing what your master tells you because he paid you. This is not science.
I actually think science will not really develop in our world until it develops a system of freedom for people to seek the truth - no matter how much it contradicts the perceived wisdom. This can only happen if - we reduce the size of governments and stop giving grants based on pre-conditions for scientists to receive funding. Science has become stunted in its purity. It is now disfunctional - and has too many people who have too many fingers in the pie. It has all become a system where self interest outweighs truth.
Science is our friend. Bias is our enemy. The peer group system is our enemy - unless we can find a way to enrich it with less self-interest.