Grant wasn't as preemptive of Meade in this incident as you suggest. Sheridan was new to Meade but well known to Grant in terms of his, Sheridan's leadership ability. Grant "suggested" that Sheridan be given a opportunity and Meade acceded to that suggestion.
"The Army of the Potomac had used cavalry for couriers, scouting, and headquarters guards for most of its existence, only
Joe Hooker had contemplated using them in an aggressive fashion, and Meade had largely continued established practice. Sheridan objected and told Meade that he could "whip
Stuart" if Meade let him. Meade reported the conversation to Grant, who replied, "Well, he generally knows what he is talking about. Let him start right out and do it." Meade deferred to Grant's judgment and issued orders to Sheridan to "proceed against the enemy's cavalry" and from May 9 through May 24, sent him on a raid toward
Richmond, directly challenging the Confederate cavalry.
[18]" Wiki.