It sure sounds like Mr. Bell made a business decision based on a personal problem with BA. But rather than criticize him for this and say it may hurt his company, you can also look at it from another angle - if BA is giving such poor customer service to him, then in his view they are likely giving as poor or even poorer customer service to his company's employees. That poor customer service can have an effect on his company and his employees so simply looking at the cost or schedule advantages with BA is being short sighted. It may have started as a personal gripe with BA but if Mr. Bell honestly feels that his company and employees will be better served by another airline that gives better customer service then we shouldn't criticize his decision too much.
He may be a small fish when compared to BA's larger corporate customers but I'm willing to bet that his move causes more damage to BA by further damaging their reputation than in any potential lost sales. If enough people do likewise, even though they alone aren't so significant, it can have a significant effect on BA and perhaps do something to cause them to improve their customer service.
Note, I don't have any connection to BA nor have ever been their customer and have absolutely no idea how bad or good their customer service may be. I'm not saying there is anything wrong with their customer service, though there may very well be based on the number of comments I've heard recently about them.