Not really puzzling (and not a loan, he's left us permanently) - he's already been there for months. Webster (according to reports) is 'minor' (implication is he'll be fit for Man U). Who else is injured ? Burn can easily slot in at CB, as could Bernardo if anyone else gets crocked.
We’ve also got Haydon Roberts who has a single 1st team appearance and has been training with them during lockdown. It seems that he is as highly rated as any centre back the club has produced at his age.