"Uh oh" for the officer! No donut!
The section you were cited for covers signs and controls at an intersection. Assuming that this "no right turn sign" is NOT in an intersection and is, instead, into a complex (on to private property) in mid block somewhere, then you may be able to win by default based solely upon the improper section cited.
22101. (a) The Department of Transportation or local authorities in
respect to highways under their respective jurisdictions, may cause
official traffic control devices to be placed or erected within or
adjacent to intersections to regulate or prohibit turning movements
at such intersections.
(b) When turning movements are required at an intersection notice
of such requirement shall be given by erection of a sign, unless an
additional clearly marked traffic lane is provided for the approach
to the turning movement, in which event notice as applicable to such
additional traffic lane shall be given by any official traffic
(c) When right- or left-hand turns are prohibited at an
intersection notice of such prohibition shall be given by erection of
(d) When official traffic control devices are placed as required
in subdivisions (b) or (c), it shall be unlawful for any driver of a
vehicle to disobey the directions of such official traffic control
And, the definition of intersection:
365. An "intersection" is the area embraced within the prolongation
of the lateral curb lines, or, if none, then the lateral boundary
lines of the roadways, of two highways which join one another at
approximately right angles or the area within which vehicles
traveling upon different highways joining at any other angle may come
Without seeing this location, I can't be sure, but generally violating a traffic control device will be cited as CVC 21461 as it has no real restriction, whereas 22101 requires the presence of an intersection of public roads.