"I don't understand," the athlete tells PEOPLE. "Why would you get all upset about one of the greatest days you could have in your life? Jo's done such a tremendous job; she asks me for my opinion [and] I give it to her."
"If she doesn't pick what I like," he says, "I'm cool with that."
Garcia, 31, star of ABC's Better with You, announced her engagement to Swisher, 29, last May. Swisher is currently "team captain" of the Art of Shaving team for the Money for Movember campaign, which seeks to raise money for cancer research.
Now, the Yankee says he can't wait for his wedding day and is speaking up about what he wants as the big day approaches.
"The planning is going amazing," Swisher says. "I've sat in on every bit of it. I know exactly what's going to happen. I'm just really, really excited for the day to get here."
Other than good food and "all of our family and friends," Swisher says the couple doesn't have a wedding theme. But he is confident that his bride will be a knockout.
"I know she's going to look like an angel on that day," Swisher says, "and I can't wait to see her."
"I think for the first time in my life, I have a woman who I could not be more proud of," he adds. "We do such a great job really pushing the other one to do better and I think that's what you have to have."
Adds the baseball star: "My old man told me a long time ago you need to marry your best friend, and I think that's exactly what I'm doing."