Was the implication of Silvio's intense anger when the kid sweeps near him that the game was rigged?

It can be argued that the gangsters did not need to cheat since the pot was raked so that would make money at it no matter what. However, a significant part of this rake was being paid by the gangster themselves since it looked like it was about half civilians and half members of Tony's crew.

Silvio in that scene where the kid is sweeping near his feet the debris of Dante's snacking makes almost too big a deal of objecting to this and my read is, the gangsters want to demonstrate that they take the game very seriously, that it is something at which they can lose just as easily as any other player can.

But I wonder if close analysis of the scenes show that members of Tony's crew ever end up big losers. In theory, a good enough poker player in an honest game could win enough that he beats the rake and part of his winnings would come from gangsters which is not something people who run the game as a business would want. Moreover, it seems like a huge sideline is getting players to borrow money which sometimes leads to what happened to Davey.

So in summary, was Silvio "protesting too much?" And was this but one indication that the game owned by Tony was not honest?

This is the scene, it is apparently the game Davey played in:

Basically what happens in the scene is that during a hand with a large pot, Tony suggests to a kid (who is working doing menial stuff like cleaning up during the game) that he sweep under Silvio's chair where indeed a lot of cheese and bread from his sandwich have fallen. In any game where a player is in a hand, the player is liable to get angry at such a distraction and Silvio (to Tony's apparent amusement) yells at the kid for a solid minute.

While this is not unreasonable behavior on Silvio's part (and the poor kid is just doing what Tony asked him to) as I said, I think Silvio is over-reacting, perhaps seeing this is an opportunity to show the "civilian" players in the game how seriously he takes such a distraction which would be a way of demonstrating that Silvio did not like losing -- and indeed, even in a game where cheating occurred, perhaps one of the gangsters would actually prefer to win a given pot than to lose one although even losing would be part of the bigger scam which was to lose all night and then manage to win at the end.