I find nothing in his record to indicate why he could not have had he choosen that route to Richmond and had he have been in charge in 1862. Grant had as bout much experience as Mac up to that point. Fought in the Mexican War and was a keen observer of the U.S. leadership in that war. Also Grant had a much keener mind that did Mac. His record as a commander and the victories he orchestrated during the war bear that out IMO. Mac was smart but he was not particularly wise...big difference.
McClellan was one of the most experienced officers in the Union Army after Winfield Scott. Second in his class at West Point (as was Lee), member of Winfield Scott's staff in Mexico, took command of two batteries in Mexico after their commanders had been wounded, breveted to Captain in that war, translated a French manual on bayonet tactics, in charge of the Company of Engineers at West Point after the Mexican War, member of Dennis Hart Mahan's Napoleon Club, engineer, commissary, quartermaster, and second-in-command of the successful expedition to find the sources of the Red River, led a survey of the rivers and harbors on the Texas coast, led a survey in Washington Territory for possible routes of a transcontinental railroad (where he came into contact with Ulysses S. Grant, who was detailed to support the effort), led a secret survey of the Dominican Republic for an anchorage and coaling station for the U.S. Navy, investigated all the U.S. railroads at the personal request of the Secretary of War (Jefferson Davis) to collect data on construction methods and costs, member of a military commission sent to Europe to observe the Crimean War, permanent promotion to captain in the 1st Cavalry, wrote the Army's manual for cavalry in the field, designed the McClellan saddle which was used by the U.S. Army for the rest of the time there was a horse cavalry in the U.S. Army, Chief Engineer of the Illinois Central, promoted to Vice President, named President of the Ohio and Mississippi Railroad and saved that railroad from going out of business, and led a highly successful campaign in western Virginia, making it possible for that area to eventually become a separate state in the Union.
Grant's record didn't come close to that. In 1861, Grant had been surprised by a counterattack at Belmont and forced to retreat. He would be surprised by a counterattack at Fort Donelson, and he would be surprised by a confederate attack at Shiloh. Grant eventually became the best general in the war, but in 1862 he still had a great deal to learn. There's nothing in the record to indicate Grant would have even thought of the Peninsula route in order to be in that position.