The disintegrate spell states:
This spell automatically disintegrates a Large or smaller nonmagical object or a creation of magical force.
Spells like Bigby's hand and Mordenkainen's sword state:
You create a Large hand of shimmering, translucent force in an unoccupied space that you can see within range.
and
You create a sword-shaped plane of force that hovers within range.
This wording suggests that disintegrate can instantly destroy either of these spells, since they are explicitly creations of magical force. But spiritual weapon states:
You create a floating, spectral weapon within range…
The weapon deals force damage, and is almost identical to Mordenkainen's sword, but is it a creation of magical force that disintegrate can instantly destroy?
Best Answer
Disintegrate won't destroy spiritual weapon
Spells do what they say they do, and spiritual weapon doesn't say it creates an object of magical force. By a strict interpretation, disintegrate won't destroy spiritual weapon.
You can house-rule otherwise by duck testing.
As your examples point out, spiritual weapon behaves much like examples of magical force created by similar spells. This is a decent argument for "spectral" being equivalent to "magical force". However, that determination is up to each table.