Charles Montgomery - Was this Ancestor a Patirot?

DAR Site has a Charles Montgomery listed as a patriot but I question it because he was a slave owner as stated in his will.

MONTGOMERY, CHARLESAncestor #: A213739
Service: MARYLAND Rank(s): PATRIOTIC SERVICE, PRIVATE
Birth: ANTE 1758
Death: ANTE 5-8-1809 WASHINGTON CO KENTUCKY
Service Source: CLEMENTS & WRIGHT, MD MIL IN THE REV, PP 160, 161; HALL OF RECS COMMISSION, EXECUTIVE MISCELLANEA, P 116
Service Description: 1) CAPT JOHN BARNHAM, 12TH BATT, CHARLES CO MILITIA;
2) TOOK OATH OF FIDELITY, 1778

RESIDENCE
1) City: BRYAN TOWN HD - County: CHARLES CO - State: MARYLAND
Created: 2019-01-28 13:31:28.883, Updated: 2019-01-28 13:31:28.883, By: ASPENCER
SPOUSE
1) MARY ANN ELDER Created: 2019-01-28 13:31:28.81, Updated: 2019-01-28 13:31:28.81, By: ASPENCER

Nat’l Num Add
Vol. Docs Child [Spouse #] Spouse
914168 1206 JOHN [1] ELEANOR ELDER