Was the intent of your email to point out that now that the problem with the vendor's equipment has been identified, you can move forward in making things better by either finding a new vendor, or trying to get the current vendor to fix the problem? If so, and you didn't say that in the email, it could be that Big Boss needs this spelled out for him.
So, while you might have been thinking, "Now Big Boss will automatically look into changing vendors, or will ask me or someone in More Appropriate Dept. to do so, and this will make things better," he may not understand that unless you actually write: "Would you like me or someone in Other Department to discuss this problem with Vendor or look for a new vendor so that we can fix this problem?"
Perhaps you thought it would be too forward to say that.
If he has a mind that just reads what is front of him, stops, and does not think any further, he may just think, "Why is DollyPond 'complaining' about this problem? We can't do anything about it, so we should just 'look into the future' by ignoring it."
If you knew him better and could trust that he wouldn't react badly, I would at this point write something like, "Yes, if we are able to correct this problem, it will help us to move forward and achieve the highest standards. I will look into it."
But I agree that that might be seen as "correcting" him, so it's probably good that you've decided not to respond.
ETA: Some people see any mention of something bad without trying to fix it as "complaining" or a "waste of time," etc. So, if your intent was not to find a solution and was just to say, "Hey, I discovered something interesting about this problem we've been having and just wanted to share it with all of you," he might not like that.