That looks like a security measure to me. Someone wanting to poison the president might taint their own shaker and try to swap it for his. Using different sizes allows the Secret Service to track them more easily, and the President knows to only use his own shakers, utensils, cups, and plates.
There are a lot of elements that seem random about Trump and his schedule. I suspect they're all security measures. Like sending a motorcade to Mara Lago while he was flying to Afghanistan for Thanksgiving. It would not surprise me to learn that there was a credible threat in Mara Lago, so he put himself on a different continent.
