No. The bottom line is that the police's right to detain him is in question. It's not a definite on either side. Terry v. Ohio upheld the police's right to stop, and even frisk a citizen, in certain situations. One of which is if there is a potential danger to the officer or the people around the area, then the police CAN stop and frisk for weapons, such as guns, knives, etc. So it's not so cut and dried.
District courts all over have made it pretty clear that a phone call reporting someone carrying a gun is not grounds for detaining or searching the individual.
United States v. Dudley, 854 F.Supp. 570, 580 (S.D.Ind.1994), the court held that a radio call alerting police to
the presence of two people in a vehicle with firearms did not provide reasonable suspicion of a
crime justifying the stop, because possession of firearms is not, generally speaking, a crime. The
court discussed in more detail the issues of firearms licensing and whether possession of the
firearm itself was a crime:
[Officer] Martin's impetus to investigate the Dudleys was a radio call alerting him
to the presence of two people at the truckstop in possession of some guns. Of
course the possession of firearms is not, generally speaking, a crime unless you
happen to be a convicted felon, the firearms are otherwise illegal, or you are not
licensed to possess the gun. Martin, presumably not clairvoyant, could not have
known, and did not know, the Dudleys and their guns met all three of these
criteria. In fact he testified he had absolutely no knowledge, or suspicion, that the
Dudleys were engaged in any criminal activity until he discovered the first sawed-
off shotgun. A telephone report of citizens possessing guns or merely engaging in
"suspicious" activity, standing alone, cannot amount to reasonable suspicion of
crime.
The court further noted that "if the stop itself is unlawful, neither Terry nor Michigan v.
Long authorizes the police to search the suspects or the suspect's vehicle for weapons, even if the
officers reasonably fear for their safety."
Just one of many, this should suffice, anymore wall of text and my brain explodes this late at night.