That plan is better than just you coming forward.
But it still might be a problem. If the person in question is the store manager it is a really difficult situation. If the owner doesn't immediately recognize your complaints as valid, it is likely the store manager will eventually find out that people went behind his back. He can make life difficult for you in countless ways.
In the various businesses where I've worked, I've seen numerous instances of managerial incompetance. I always assumed it was because the owners didn't know what was going on at the employee level. But after I worked my way up the managerial chain my perspective changed. For 3 years I was the general manager of a large wholesale distribution company and it gave me a lot of insight into things that casual employees don't get to see. Very often senior management knows that a particular manager or employee is bad news, but they choose to keep them for a variety of reasons. The bad employee may be related to the owner's family, or might be a family friend, or more often may bring a particular skill that is hard to find elsewhere.
We had a transportation manager who worked a shift that began around 4:30 in the afternoon and ended in the wee hours. He didn't get along well with his wife, so he'd work very late into the night just to be away from her. We knew that he had poor management skills, but he knew our truck fleet inside and out, and he was the only person who would work those hours that we needed at the salary we were paying him. So when he'd muck things up with one of our drivers we would just smooth it over in the front office.
At another job I had, the senior management team hired a manager for a division, and he was given the task to save money no matter what the cost. The people who worked under him suffered because of this. Whenever they'd bring complaints about his mis-management they would fall on deaf ears because the senior management team was satisfied with the job he was doing in saving money, so they considered the hurt feelings of his employees as collateral damage. Of course it ended up hurting the company in the long run, but in the short run it baffled a lot of people why that guy got away with so much ineptitude (it was because his sole reason for being there was to save money, not effectively manage the unit.)
These are two simple examples I've witnessed where good employees brought concerns about a manager to senior management, but nothing was done about the problem manager. I just offer these as a caution in case something like this happens in your situation.
If you decide to go forward with this, you have to be ready to accept the consequences if the problem manager finds out that you went behind his back. You may be right about him being bad, but unless you get the owner to agree with you, it may be worse for you afterward.