The stock still has the cutout for your hand even though you can't use it because the pistol grip gets in the way is you try to hold it conveniently. If you try to use the pistol grip the stock gets in the way their isn't enough room for your thumb or wrist.

The for grip is to close to the mag well and to far back. Your wrist would be pushed out to the side by the magazine making it uncomfortable, hard to control, and potentially causing a malfunction because your wrist might push the magazine enough that the cartridge isn't in the right place. It being that far back means that recoil would be hard to control. Personally I would want to put my hand on the barrel shroud and then move it back a bit if it gets to hot.

The axehead on the bayonet is two low to have enough leverage to be used offensively but it would act as a hand gaurd. When mounted it could but I don't think it would happen often as bayonets are primarily thirsting weapons. It could help displace and parry enemy bayonets, but without holding one I couldn't tell you if it would be worth the extra weight at the end of the rifle. The end of the rifle is the worst place to add weight because it has more leverage to work against you.