The hypothesis is out there, but it's being taken seriously by many in the scientific community. The Breakthrough Listen Initiative, an organization established this year to look for alien life that counts Stephen Hawking and Mark Zuckerberg among its board members, finds the evidence promising.
"The one in 10,000 objects with unusual spectra seen by Borra and Trottier are certainly worthy of additional study," Breakthrough Listen said in a statement promising follow-up research. "However, extraordinary claims require extraordinary evidence.
“It is too early to unequivocally attribute these purported signals to the activities of extraterrestrial civilizations. Internationally agreed-upon protocols for searches for evidence of advanced life beyond Earth (SETI) require candidates to be confirmed by independent groups using their own telescopes, and for all natural explanations to be exhausted before invoking extraterrestrial agents as an explanation.