Sure, maybe it was tongue in cheek and him having a ditzy "guy" moment.
But we're doing communication and boundaries at Trauma School (rolls eyes!), and my T would no doubt go for the assertive communication route to make sure that he realises what he did and why it's outta line. Like, "I felt unattractive and not good enough for you when you suggested I get implants. Even if it was a joke, it was hurtful, and I'd prefer it if you didn't suggest my body needs surgery in the future."
You're allowed to love your body, and in a really healthy relationship, boh parties know that both parties find the other physically attractive, yeah?