I carefully choose words such as "possibly" and avoid making hard and fast statements. Another one is "unknown" - 'cos it is.
Compare Vincent and Rains. It's nomming Rains while he's still alive (possibly similar to what happened to Lambert). With Vincent, Kevin is drawn to his screams - possibly suffering the same fate as Rains, but when he gets there, Vincent's screaming has stopped. If it's only been stopped for a matter of seconds, we have a very similar death to Lambert and Rains, rather than the more popular view of eating him.
Or it could be something different entirely.