Wouldn't it be easier to scan for enemies using helmet mounted NVGs? Just seems like overkill having an IR laser for passive aiming and a heavy night vision scope.
IR laser passive aiming is only good for close range. At 100m+, the laser blooming and zero magnification of your typical helmet mounted NVG will mean you will really struggling to make precise shots. You should still be able to easily hit man sized targets out in the open, but a reduced target like someone actually taking cover, would be much more challenging.
A dedicated rifle scope will allow you to make much more precise shots to far longer ranges than is practical with IR laser passive aiming.
Besides, it’s not a choice of one or the other, this setup allows you to do both. You can go IR laser passive aiming for quick close up shots and use the thermal scope for long range precise shots and for greatly enhanced target detection.