Uncommitted objectives are counted when calculating load. Load is a measure of how much work a team can realistically accomplish in a PI. Load is calculated by adding up the story points of all the committed and uncommitted objectives of a team. Committed objectives are SMART goals that reflect the value that each team intends to deliver in a PI with high confidence. Uncommitted objectives are stretch goals that reflect additional value that each team may be able to deliver in a PI if they have extra capacity or time.
Uncommitted objectives are not included in the commitment or the business value scoring, but they are included in theload to account for their potential impact on team capacity. References: PI Planning, Team PI Objectives