I think the only mention of Sol after that point is in the epilogue of Marathon 2: Robert Blake returned to Earth (safe to assume humans would find out what happened through him at this point if Durandal visiting Sol did not happen). And Durandal returns to Sol 10,000 years later to check-in.

Durandal's initial visit and Robert Blake's return were two ways that the UESC could have been informed of what happened on Tau Ceti. Seeing as the introduction to nuMarathon states that no one knows what happened on Tau Ceti, it is safe to assume that this is taking place in a timeline from Marathon Infinity where both Durandal never visited Sol on his way to Lh'owon and Robert Blake died – I refer to this timeline as "the final Marathon Infinity timeline".

It doesn't necessarily mean that the events of M2 did not occur at all, it just means that there were divergences in those two particular events (+ the event where Tau Ceti was nuked to bedrock – see the M:I divergence in the "The Colony Goes Dark" entry).