You can not win your argument with the notion that light speed travel is imposable for bio genic beings. ( is that what you said, ? ) That may well be so. But that is not resson enough to prohibat alien visatation. As has been shown. A craft useing excelaration force of 1g, could quiet easly do the excelarate to halfway, and deselarate into orbit. all in about 12 years. The fact that we only live into our 80's is not an issue for a alien life form that lives for 3 hundred or so.... All I am trying to tell you is to be open to difering ideas. Just becouse you and I can not yet do some thing that does not make it imposable. Just Highly unlikly,.
To diswade the avid alien nut, I try to explain the size of the Universe and the time line since man has roamed the Earth for not yet one million years. This Solar system of ours is just four and a half bilion years in a galaxy that would seem to be about therteen point eight billion years old. The chance of us being alone in the universe is nill. But the time and distance between life forms might well prohibat us ever making contact.