Here's the problem:
Even assuming that the salt disparity actually exists (and I don't actually grant that, as it seems to have been disproven already) it in no way overrides the incredibly large amount of evidence we have to support a significantly older Earth.
To say that teh Earth is a few hundred, a few thousand, or even 100 million years old requires evidence of sufficient strength to challenge everything we know about:
Geology
Radiology
Biology
Astronomy
Plate tectonics
Vulcanology
Planet formation
I could go on.
The age of the Earth is established not by one single piece of evidence, but rather by multiple independent sources that all interdependently establish the same age range for the Earth. Even if the amount of salt in the ocean suggested that the Earth was only 10,000 years old, it still would not override all of our
other evidence surrounding the age of the Earth.
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