Tucking in polos and t-shirts into jeans can be done imo, but I consider it an advanced move so to speak, because you must have confidence and a good build, great fit, and kick ass belt to pull it off. When it's done right I think it looks a thousand times better than that amjack faux tuck look that I see everywhere around here in Hollywood.
And unsurprisingly, it looks damn good. I should've added for clarity that like all rules, it's kind of worthless, but accurate far more often than it isn't. Fit's what matters, and it's basically the difference between you and this. By the way, those second boots kick ass. What are they?