Found a good discussion of AIS and VHF, especially explaining splitter loss. Here is the link:
and have attached the pdf.
Page 5 in the pdf explains splitters and their losses.
I think one might come to the conclusion that a splitter compromises safety.
Even though the splitter will (typically) have amplification on the received signals (not on transmit!) amplification will increase both received signal and add noise. As far as transmission there will be losses, minimally attributed to the additional connections and possibly do to splitter design. It is hard to determine all this as info about the splitter design may be hard to find. Sometimes you can tell from the specs but rarely so.