They don't necessarily have to kill them to take their abilities when Vegapunk can recreate df abilities like Pacifista's lasers from Kizaru, Momo's df and so forth.
But yeah, i like the idea that he might have Diamante's ability.
But yeah, i like the idea that he might have Diamante's ability.
Anyway it's just a theory that comes from the fact that S-Jinbe appears to have Señor Pink's ability.