Guess you're not up to date on the carbon dating actually used.
The sample used was from a corner the Catholic Church felt was not essential to the shroud. It had been contaminated in a fire, and restored in a way that invalidated its use for carbon dating purposes. In addition, it was subsequently shown that the individual fibers in the shroud had grown a biological "sheath" that was not removed prior to testing, and added new biomass to the original material. Since this new growth was obviously younger than the shroud itself, it undoubtedly changed the tested age of the sample.
Attempts have been made to mathematically correct for these problems. You may choose to dispute the math, but the correction results in a first century date for the shroud.