Were PGMs only meant to escort PT boats near the attack area?

Were the U.S. PGMs intended only to escort PT boats near the attack area rather than accompany their attack and withdrawal?

No. That was not the design brief, and the U.S. Navy itself judged the PGM-9 too slow for its intended work and reassigned the class to minesweeping support.

The suggestion would make the low speed easier to explain, but it does not match the requirement given to the designers. PGM-9's anti-aircraft battery also did not transform it into an ideal transit escort. The decisive evidence is operational: the U.S. Navy judged the boats too slow and moved them to covering minesweeping ships instead of PT-boat operations. A plausible retrospective use should not be confused with the mission the class was supposed to perform.