Not a good idea for three reasons:

• the assumption that this will stop lawsuits is very generous, especially when we consider that there are other countries than the US that have lawyers and IP too
• putting such an important task in the hands of a government that might be controlled by whatever extremist possible in the future is a bad idea; who controls the past, controls the future and parties could delete parts of the past at their will
• a less dystopian thought: future governments might simply cut the funding or restrict the archive to US content only because "why shouod they pay for other contries' history?"

A legislative approach that protects what the archive does would be a much more reasonable approach.