There are reasons beyond the word choice in this particular context that make me lean toward the inclusive interpretation.
One is that non-self implies that there isn’t a meaningful distinction between “you” and “other beings.” Another is that there are instances in the suttas of explicit instructions to avoid self-harm. For example, in MN 61:
When you want to act with the body, you should check on that same deed:
‘Does this act with the body that I want to do lead to hurting myself, hurting others, or hurting both?
[…]
‘[…] It’s unskillful, with suffering as its outcome and result.’ To the best of your ability, Rāhula, you should not do such a deed.
Similar instructions are repeated for acts of speech and of the mind, too.
So it seems reasonable to me to extend this thinking to the cultivation of mettā as well.