Why not switch the block behind the sign when the server is online or offline?

So, as in the title, why not change the block behind the sign?
Here is the code:

HTML:

    public void updateSign() {
        if (plugin.getConfig().getString("options.background").equalsIgnoreCase("wool")) {
            updateBackground(Material.WOOL, getStartingColor(motd));
          } else if (plugin.getConfig().getString("options.background").equalsIgnoreCase("glass")) {
            updateBackground(Material.STAINED_GLASS, getStartingColor(motd));
          } else if (plugin.getConfig().getString("options.background").equalsIgnoreCase("clay")) {
            updateBackground(Material.STAINED_CLAY, getStartingColor(motd));
          }
    }

      private int getStartingColor(String s) {
        if (s.length() > 1) {
          if (s.toCharArray()[0] == '§') {
            switch (s.toCharArray()[1]) {
            case '0':
              return 15;
            case '1':
              return 11;
            case '2':
              return 13;
            case '3':
              return 9;
            case '4':
              return 14;
            case '5':
              return 10;
            case '6':
              return 1;
            case '7':
              return 8;
            case '8':
              return 7;
            case '9':
              return 3;
            case 'a':
              return 5;
            case 'b':
              return 9;
            case 'c':
              return 14;
            case 'd':
              return 2;
            case 'e':
              return 4;
            case 'f':
              return 0;
            }
            return 0;
          }
          return 0;
        }
        return 0;
      }

      private void updateBackground(Material mat, int color) {
          try {
        Location loc3 = this.getLocation();
        Sign s = (Sign) loc3.getBlock().getState();
        if (s.getType() == Material.WALL_SIGN) {
          BlockFace bf = ((Directional)s.getData()).getFacing();
          Location loc2 = new Location(loc3.getWorld(), loc3.getBlockX() - bf.getModX(), loc3.getBlockY() - bf.getModY(), loc3.getBlockZ() - bf.getModZ());
          Block wall = loc2.getBlock();
          wall.setType(mat);
          wall.setData((byte) color);
        }
          } catch (ClassCastException e) {
              e.printStackTrace();
              plugin.logConsole(Level.WARNING, "[Signs] Error: " + e);
          }
      }

Here is the config:

Open! (open) Open! (close)

options:
background: glass

Images:

Open! (open) Open! (close)

Online sign:

Offline sign:

 

@timtower
No.

 

@timtower
Yes and bukkit + spigot. (1.8)