Sure, I would even say the most modern :-)
That case is indeed ruling out window size handling.
Assuming your terminal use a xterm compatible emulator (dtterm, gnome-terminal, rxvt and the likes are ok) I think you could write a script that set these tty settings to their correct values. Of course that wouldn't be very useful.
You are correct although I doubt the OP was concerned about that case. Its use is slowly fading though with modern LOM based on ethernet vs serial lines. Agreed. POSIX is currently of no help here.
What specific risks involved with awk are you thinking of ?
I would say that differently: Sun is extremely reluctant to put its existing customers/users at risk by breaking compatibility from older Solaris releases to newer ones with providing a new and incompatible version of a commited standard command. That is the same reasoning that makes /bin/sh such a featureless and disappointing shell.
Of course, everyone is free to use nawk and ksh(93) like I do.
That is not that difficult to write although not particularly reliable if the shell script is interactive. eg:

Code:

$ cat winch.ksh
#!/bin/ksh

function winch
{
    eval $(/usr/openwin/bin/resize)
    echo new width=$COLUMNS
    echo new height=$LINES
}

trap winch WINCH
echo "Resize the window to exercise the handler:"
for i in 1 2 3 4 5 6 7 8 9
do
    echo $i
    sleep 2
done