checking utmp entry

have a question about something I saw in some large code. The author
checks for the user tty using the following

Code:

---

while ((err = getopt(argc, argv, "t:s:wrp:")) != -1)
    switch (err) {
    case 't':
      tflg = 1;
      strncpy(tsk[0].u.ut_line, optarg, sizeof (tsk[0].u.ut_line));
      break;

---

And then later on,

Code:

---

int check_in(tty, in)
    char *tty;
    int  in;
{
  int i;

  for (i = 0; i < in; i++) {
    if (!strncmp(tty, uinfo[i].ut_line, strlen(tty))) {
      return 1;
    }
  }
  return 0;

}

---

The question is why would this person copy the tty arg into
tsk[0].u.ut_line? Ie why not just do something

./name cda -t ttyp4

Then in the program, just check if the arg ttyp4 (via check_in())
passed on the command line was a vaild tty.