Does this stuff work and can it be used on saddles?

My horse has decided that he likes the taste of leather. Especially the leather on my grandmother's new-ish Cricle Y saddle. This stuff apparently stops horses from chewing on things but would it be ok to use on a saddle? Here is some info on it:
NEW!!! OLD MacDONALD's® STOP CHEWING TRAINING AID is guaranteed to stop repeated chewing. Colorless formula does not stain. Apply Old MacDonald's® Stop Chewing Training Aid to items that your dog and other pets like to chew on. Spray once a day or less depending upon your pet. Can be applied to furniture, rugs, shoes, wood, silk, plants and hair coat. Non-toxic: made with hot peppers.

You can find it at:
http://www.jmsaddler.com/OldMacD_products_table.php

Any opinions or other ways to get him to stop the chewing on saddles?
READ THIS!:
He's getting to the saddle while it's on another horse when we go camping. They're tied up next to each other on lead lines because that's where they "live" while we're there. They're apparently just long enough for him to reach the saddle if the other horse is facing the right way. We don't find it necessary to bring a small fence that my gelding would happily knock down even if it had electricity going to it. And he's only done it twice. The first time I had the horses saddled and went to go grab my bridle. When I came back to him he was chewing on it! The second time I was sleeping still and my grandpa saddled them up. When he came to wake me up we walked to the horses and he was doing it again. And don't say that I shouldn't "leave my horse unattended" Both times I was gone for literally under a minute, and you cannot tell me that you've never gone to grab something before and left your horse tied.
It says "or other animal..."
and in the picture in the magazine it shows a horse chewing on what looks to be a halter.

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