To build on what Andrew has said here, OCXOs by definition cannot be referenced to anything else. They are entirely self-referential, so without doing some really questionable signal manipulation after the fact, you can’t match the speed of an OCXO to anything else - including a 10MHz reference.
That’s why the only place we use OCXOs is in Master Clocks, as they don’t need to lock to anything else. They are the Master. By contrast, everything else (DACs, Upsamplers, Transports etc.) uses VCXOs. We need to manipulate the control voltage used to adjust the absolute frequency to match a source device if no Master Clock is being used, or to lock to a Master Clock signal correctly if one is being used.
So with Varèse, where the Clock uses an OCXO for the 22MHz oscillator and a VCXO for the 24MHz oscillator, there’s no way to have a reference input as that 22MHz OCXO cannot be locked to anything.
As an aside, The inclusion of the 10MHz port on the Vivaldi Clock never was a statement that it should be used with an external reference outside of the factory. As Andrew says, it’s simply a function used during calibration that remains exposed. Pure speculation and I’m sure some folks here may remember (@AndrewS?), but I would wager that when Vivaldi was originally launched, there were very few - if any - “audiophile” 10MHz clocks on the market. The former may well have spawned the latter.
Ultimately, in the years since, nobody has broken mathematics enough to divide 10,000,000 into 44,100 or 48,000 with an integer, so our stance on 10MHz clocks is the same as it always has been.