I am not his ad campaign manager or landing page optimizer. I just gave a quick tip. If I were to do it I would have done it differently. The idea is not to say that this is the best way to go about it. The idea is to steer him in the direction of keeping it simple. If you have a better tagline you can suggest it.

And yes, the tagline I mentioned may not be the best but it will definitely get him more conversions compared to the one he currently has. At the end of the day conversions matter the most. No sales, no business. Doesn't matter how much analysis you do.