The Original Series star almost had a cameo in Star Trek (2009), but it would have been confusing for Trek canon.

TNG succeeded in carving its own identity from TOS with help from a bizarre rule forbidding the mention of "Spock." The rule against saying "Spock" was enforced by executive producer Rick Berman ...

In Star Trek lore, few symbols are as iconic as the Starfleet insignia—a delta-shaped emblem that has come to represent the spirit of exploration and unity in the United Federation of Planets.