I mean, the first sentence of the preprint is "This paper characterizes the first protein to be discovered in a meteorite." The Significance section states that

I mean, the first sentence of the preprint is "This paper characterizes the first protein to be discovered in a meteorite." The Significance section states that "[the preprint] is the first report of a protein from any extra-terrestrial source." And they claim that their evidence[0] that the protein is not a terrestrial contaminant is quite strong, so I would say that the confidence level of the researchers matches the title exactly. [0] For example, from the conclusion: "The average molecular deuterium excess above terrestrial is (25,700 ± 3,500)%, or a D/H ratio of (4.1 ± 0.5) x10^-3, comparable to cometary levels, interstellar levels and also equal to the highest prior report in micro-meteorites."