VA was literally there waiting for an opportunity to tag Saturn… it doesn’t take much critical thinking skills to realize that the man who’s able to teleport without a trace was the one who teleported the food which appeared without a trace or Luffy who disappeared without a trace.
And it doesn’t take much critical thinking skills to realize that if that was the case, Oda would have solved the mystery at the very same moment VA was presented or at least now, the last time we saw the BBP in EH and the last time we would ever talk about this.
So, instead of thinking that VA was spying on them, did that and then Oda magically forgot to tell us, wouldn't you consider that maybe was one that:
- was there (confirmed, not theories)
- was seen moving after the food was delivered;
- was worried about Bonney and Sentomaru the second before;
- had "..." after the food was delivered;
- used his own ramen bowl;
- Is probably the fastest character in the verse;
- and probably Is going to appear next chapter?
Just saying.