Why not start the thread anyway, Grandad ? When Gransnet was first launched, in 2011, the first members were mostly new to social networking so they just started conversations on subjects they were interested in or wanted to hear other people's views on. The threads reflected what the posters wanted to post. They didn't know how to "represent the thread" because they were new to posting. Other people replied and the threads represented themselves, according to how those posting said what they thought. That is the only way that a non-moderated forum without a permanent host and "compere" can progress.
If you can compose the posts that you have usually published, you can frame an introductory post under the "Health" topic (topics are listed in the page acessed bythe relevant button above". Others will reply. You may well get a preponderance of female replies, but if you say that it is a serious enquiry into why men are so reluctant to take action on their health, you will get serious opinions.
If you really want male replies, you could send private mesages to the men in the membership, asking them if they could help you out by posting.
You have to be pro-active and take positive steps yourself, not complain about the situation and nag someone else to change it all to suit you.