From PHB p. 191
You can move through a nonhostile creature’s space.
Whether a creature is a friend or an enemy, you can’t
willingly end your move in its space.
From PHB p. 290
An unconscious creature is incapacitated (see
the condition), can’t move or speak, and is unaware
of its surroundings
From PHB p. 289
An incapacitated creature can’t take actions or
As an unconscious creature can't take any actions, it clearly can't take hostile actions so qualifies as non-hostile. By the RAW you can move through the space irrespective if the creature is friend or foe.
As this is written, you cannot willingly end your move in an unconscious creature's space. Presumably you could end your move in a dead creature's space as it is no longer a "creature" by virtue of being an ex-creature (possibly even an ex-parrot).
This interpretation is bloody stupid. All sensible people should play that an incapacitated creature's space can be willingly ended in.
As an aside, how does standing in the creature's space protect it anyway? If I am attacking I can choose to attack you or your unconscious colleague.