I was just sort of trying to be funny. But, what you say is only technically and marginally true.
There is generally an inflated concern about aerosolization because of numerous studies that demonstrate the effect. The vast majority of those studies are based on commercial high-volume, pressurized land toilets and apply much less to an average household high-efficiency toilet (like orders of magnitude less) and certainly even less to most marine heads (though I know of no study that looked at that, specifically). The general consensus is that the main contributor to aerosolization is pressure. More pressure = more aerosols traveling farther. So, yes, it occurs with a marine head, but likely just barely.
Also, a teak grate is not exactly a petri dish. It is usually dry, exposed to light and air, and doesn’t provide a food source. Bacteria without a wet, nutrient-rich environment die quickly (often within hours). In fact, there is considerable evidence that microbes die out more quickly on wood than on many non-absorbent surfaces. (For example, read studies on wood vs plastic cutting boards. Also, similar studies demonstrate this in a medical setting - that wood can outperform steel, glass, and plastic.)
In practice, bilge pumps, wet foulies, and galley sponges are all much bigger vectors of “boat germs” than a teak grate in the head.
All I'm saying is that, if you are bothered by the science of it, then you probably should not be, because science doesn't support any elevated health/sanitation risk, as compared to the alternatives. But, the bottom line is that, if it bothers you, you should remove/replace it, obviously. Just understand that it is probably not in the top 5 pathogen vectors on your boat. If you are genuinely concerned about aerosols, the MUCH greater issue is anything you would touch with your hand.
The only thing that wouldn't make sense is to replace it with an absorbent mat/rug.