When you have 4 or more creatures in the graveyard and activate Bloodsworn Squire's ability, it should get indestructible AND transform.
I did this multiple times while Bloodsworn Squire was attacking (2x same turn, 1x a few turns later) and it did not transform.
Activating the skill while Bloodsworn Squire is NOT attacking, does work.
(I did not test whether it works while Bloodsworn is tapped and not attacking)

EDIT: It did gain indestructible when the skill resolved