Ouroboroid gives +1+1 counters after he's been turned into a food by Shelob

[Lunafreliana]

I destroyed [[Ouroboroid]] with a spider and it got turned into a food token thanks to [[Shelob Child of Ungoliant]]. When I entered the battlephase Ouroboroid buffed all my Creatures with a +1+1 counter, even though X should have been 0

[github-actions]

Ouroboroid - (Gatherer) (Scryfall) (EDHREC)

{2}{G}{G}
Creature — Plant Wurm
1/3
At the beginning of combat on your turn, put X +1/+1 counters on each creature you control, where X is this creature's power.

Shelob, Child of Ungoliant - (Gatherer) (Scryfall) (EDHREC)

{4}{B}{G}
Legendary Creature — Spider Demon
8/8
Deathtouch, ward {2}
Other Spiders you control have deathtouch and ward {2}.
Whenever another creature dealt damage this turn by a Spider you controlled dies, create a token that's a copy of that creature, except it's a Food artifact with "{2}, {T}, Sacrifice this token: You gain 3 life," and it loses all other card types.

[muz]

This looks like rule 208.3 isn't being applied correctly;

208.3. A noncreature permanent has no power or toughness, even if it’s a card with a power and toughness printed on it (such as a Vehicle). A noncreature object not on the battlefield has power or toughness only if it has a power and toughness printed on it.

I don't think it's right to go and manually set PT to 0 on Shelob's custom effect, and looking at Ouroboroid, the trigger currently uses SourcePermanentPowerValue.NOT_NEGATIVE

I'm wondering if the right fix is to implement this at the DynamicValue that calculates this value with something akin to:

diff --git a/Mage/src/main/java/mage/abilities/dynamicvalue/common/SourcePermanentPowerValue.java b/Mage/src/main/java/mage/abilities/dynamicvalue/common/SourcePermanentPowerValue.java
index e6511a9357..f975172058 100644
--- a/Mage/src/main/java/mage/abilities/dynamicvalue/common/SourcePermanentPowerValue.java
+++ b/Mage/src/main/java/mage/abilities/dynamicvalue/common/SourcePermanentPowerValue.java
@@ -25,6 +25,9 @@ public enum SourcePermanentPowerValue implements DynamicValue {
         if (sourcePermanent == null) {
             return 0;
         }
+        if (!sourcePermanent.isCreature()) { // TODO: Does this need to also check the Zone for being in play
+            return 0;
+        }
         int value = sourcePermanent.getPower().getValue();
         if (allowNegativeValues || value > 0) {
             return value;

Dynamic Toughness values would also need something similar.

The thing throwing me is the handling on the second part of the ruling wherein if the card (not on-battlefield-permanent) is being evaluated, does this still handle Vehicles etc correctly where the printed value should be used