Astronomers are extremely interested in detecting biosognatures in exoplanet atmospheres. This is one of the hottest topics in astronomy right now. They're just

Astronomers are extremely interested in detecting biosognatures in exoplanet atmospheres. This is one of the hottest topics in astronomy right now. They're just not interested in idle speculation about whether or not Oumuamua is a light sail. If there were some measurement that could be done to learn more about Oumuamua, then astronomers would do it, but it's a tiny object that's quite far away now. Most astronomers simply believe that the most likely explanation for the anomalous acceleration is that there was some undetected outgassing from the rock. That's much more plausible than the idea that this one particular object is an alien spaceship - not because there couldn't be alien spaceships somewhere out there, but because there are so many rocks floating around in space. The one thing that you really can't get funding for is SETI, but that's not the fault of astronomers. That's the fault of congresspeople who ridiculed the search for "little green men" in the 1990s and barred NASA from funding it. Almost all astronomy funding comes from governments, so a government ban on funding a particular line of research means that that research basically won't happen.