It's the only trace of Simeon I've been able to find so far. He did not appear at all on Rootsweb World Connect, FamilySearch or Mocavo. According to the site
[The First Massachusetts Regiment] was first authorized on 23 April 1775 in the Massachusetts State Troops as Paterson's Regiment under Colonel John Paterson and was organized at Cambridge, Massachusetts. It consisted of eleven companies of volunteers from Berkshire, Hampshire, Suffolk, Middlesex, Worcester, and York counties in Massachusetts and the county of Litchfield in the colony of Connecticut. The regiment was adopted into the main Continental Army on 14 June 1775 and was assigned to William Heath's brigade on 22 July 1775. On 1 January 1776 the regiment (less two companies) was consolidated with Sayer's and Sullivan's companies of Scammon's Regiment; re-organized to eight companies and redesignated as the 15th Continental Regiment of Heath's Brigade.
On 1 August 1779 the regiment was assigned to the Highland Department, which would fit with this assignment. The department was based at West Point, New York.
Because Paterson recruited men from Berkshire County, it is possible that Simeon Van Gilder was a descendant of John Van Gilder. I don't know if it could ever be proved one way or another.