Scientists can do what they please in their private lives and most of them do. What statements they make are up to them. If they are personally honorable, these statements will be an honest opinion based on years of experience, not just of science but of ordinary life itself, and many facts and observed probabilities. This is ethical.
Why can't scientists know about philosophy, metaphysics, religion etc? Dr, Norman S, who was an authority on surface chemistry and explosives also wrote stage plays. Dr. F, a forensic chemist was also known as a potter. I have known a physicist who was a highly competent musician and had played in symphony orchestras and also released a few CDs. It's pretty clear that Albert Einstein was familiar with the work of 17th century philosopher Baruch Spinoza if not other philosophers, and so on. What do you think scientists do with their spare time? Watch reality TV?
Are you able to tell me when these assertions are not empirically based? If some proportion of the public cannot distinguish between scientific claims and personal opinion then that is not the responsibility of the scientist. It is not her problem that some proportion of the public is stupid, ignorant or misinformed. While anyone, scientist or not, might wish that what they say is not distorted or deliberately misrepresented by the media, there is in effect little or nothing she can do about it if it is distorted or misrepresented, particularly when that is done in another country.
Allow me to point out that religion is based on practically no evidence at all. There is hardly a entire chapter in the Bible which one could say with absolute certainty was entirely objectively true. That is not to say the Bible contains no facts, but Charles Dickens' "Bleak House" or any realistic novel contains facts too. I'm no authority on the Koran but from what I have seen in a copy I have here the situation would be similar.
Further, the religious have had many thousands of years to produce objective, irrefutable evidence of any god, any afterlife, any soul, spirit or whatever it is called, any angel, nymph, demon, dryad, gnome, elf, devil, djinn or all the rest of the demigods and supernatural beings of myth and legend. This they have signally failed to do. Is it therefore ethical for the religious to make pronouncements of a philosophical, religious or scientific kind? What is the objective basis for many of the assertions made by the religious here and elsewhere?
Is it ethical for a fundamentalist pastor to misuse his position of respect and authority in religion to make statements about the empirical sciences, which from their content show that he knows little and understands less, (when he is not directly lying) so as to to sway public opinion towards his own philosophical/ metaphysical ideas?
Perhaps not, but they do often enough to be noticeable.