I guess you could make a trivial pipe something like this:
/* ff - flush fonts
Copies standard input to standard output removing Genera font information. */
#include <stdio.h>
#define FONT_START ''
main ()
{ int c;
int flag = 0;
while ((c = getchar()) != EOF) {
if ((c == FONT_START) || flag) flag = !flag;
else putchar(c);
}
}