Unfortunately the case with men (and women) who are in this situation tend to not be a good candidate for a hair transplant due to the donor hair (hair in the back). Cases like these, doctors have no other suggestion for them except for maybe doing PRP shots or even telling the client to use fibers to create that density.
When it comes to a legitimate solution to address the hair thinning, Scalp Micropigmentation is the solution out there to address the hair thinning. Here are some examples of clients of ours who had their scalp shaded essentially to remove the appearance of the scalp. These clients of ours are not required to shave their head down for our procedure. What we do request is bring it down to the shortest desired length that you wish to keep it at. We will use our pigments to blend in with that length but feel free to grow it out longer if you want that style.