a preliminary submission has not passed a peer review with the rigor of scientific defense.
these sorts of things may be passed among researchers for extended periods of time [years] until all the kinks are worked out of the thesis and a working theory with no known exceptions and independently confirmed agreement of results occurs.
What exactly is the standard of peer review you're expecting? Unless you have reason to think they flat out fabricated the data, the analysis is probably no better or worse than your garden variety nature or science or cell paper.
it's on bioarxiv, what exactly does 'too new' mean?