Some things are neither all good or all bad. Actually, that's true about just about everything.
They aren't trying to tell you this type of radiation is good or bad, they are telling you specifically it was effective in blocking amyloid plague dementia.
By the way, the tumors that are about 3.5x more common with cell phone use is the non-cancerous type. Tumor and cancer are not synonyms. Not that any tumor is a good thing, of course.
Beyond the cell phone issue, this does give further insight into Alzheimer's Disease. It doesn't give a lot answers, but it does give a pointer to which questions need to be asked. And if you don't ask the right questions, you aren't going to useful answers.