a) reason to keep them there b) reason to get them out of there, possibly Sirius' house. c) reason to hand them over to the ministry d) ...this is Dumbledore. N/A. Power level nothing, he's got spells that would totally blindside Junkyard types. e) He's not actually that good at hiding stuff that large.
He might find a safehouse for them, but Hogwarts is already a safehouse for people that are a higher priority to him, and he's having a lot of trouble keeping it a safehouse already without adding another possible internal threat/reason for the Ministry to give him a hard time.
Looking at your list:
b) reason to get them out of there, possibly Sirius' house.
c) reason to hand them over to the ministry
d) ...this is Dumbledore. N/A. Power level nothing, he's got spells that would totally blindside Junkyard types.
e) He's not actually that good at hiding stuff that large.
He might find a safehouse for them, but Hogwarts is already a safehouse for people that are a higher priority to him, and he's having a lot of trouble keeping it a safehouse already without adding another possible internal threat/reason for the Ministry to give him a hard time.