[You just say that because he's cuter than you now.]
Come now, don't exaggerate. [But with that said, he sighs.]
It is true this is inconvenient and pointless - there are hardly any situations where having a child's form is the more advantageous option.
[There's a reason Sebastian avoids it when forming his contracts... And, being a shapeshifter, he's not that bothered by having his appearance tampered with.]