Few minutes ago I received an email from Latam confirming that there are no residency restrictions anymore so I bought the ticket, even though the warning appeared again during the process of booking.I used the Peruvian Spanish site.

This is is the message: "la tarifa que seleccionaste es exclusiva para residentes. El dia de tu vuelo tendras que acreditar esta condicion en nuestros mostradores o se podria cobrar una multa."