Relevant text:
Sneak Attack
Beginning at 1st level, you know how to strike subtly and exploit a foe's distraction. Once per turn, you can deal an extra 1d6 damage to one creature you hit with an Attack if you have advantage on the Attack roll. The Attack must use a Finesse or a ranged weapon.
You don't need advantage on the Attack roll if another enemy of the target is within 5 feet of it, that enemy isn't Incapacitated, and you don't have disadvantage on the Attack roll.
The amount of the extra damage increases as you gain levels in this class, as shown in the Sneak Attack column of the Rogue table.
Spiritual Weapon
You create a floating, spectral weapon within range that lasts for the duration or until you cast this spell again. When you cast the spell, you can make a melee spell attack against a creature within 5 feet of the weapon. On a hit, the target takes force damage equal to 1d8 + your spellcasting ability modifier.
As a bonus action on your turn, you can move the weapon up to 20 feet and repeat the attack against a creature within 5 feet of it.
The weapon can take whatever form you choose. Clerics of deities who are associated with a particular weapon (as St. Cuthbert is known for his mace and Thor for his hammer) make this spell’s effect resemble that weapon.
My DM ruled that it granted Sneak Attack, based on the fact that a floating spectral weapon would be just as distracting as a live creature, but I could see a case for either
Best Answer
It's a DM ruling, but I'd say no.
As you show, nothing in the text of the spell discusses whether it's a valid helper for sneak attack. Therefore, we have to look at other factors.
The Sneak Attack text says,
But is a spiritual weapon distracting? Note that it doesn't do anything unless ordered by its caster. In particular, it can't make opportunity attacks. Consider the text for opportunity attacks:
However, you can move heedlessly past a spiritual weapon, because it's not on guard and looking for an advantage. In the absence of any other text, it's simply floating there until commanded. Thus, on your turn, it's not posing an immediate threat the way another creature would.
Additionally, Sage Advice says no, though without an explanation.