Do we criticise Jonathan Harker for the things he does in Dracula's castle including entering it?
For that analogy to be valid, the existence of vampires and the threat they pose would have to be widely known in the novel, which isn't the case. No credible scientist on earth would disembark, unprotected onto an alien world, especially one that already has confirmed life on it. There's just as high a likelihood that you'd infect the local ecosystem with something in/on your body as vice versa.
Yep, work its way into the suit, eat through a filter perhaps! Simple logic fixes like this across the film could have helped temper all the check-your-brain-at-the-door criticism it received... which would be fine if it was just a light popcorn film, but Covenant treats itself so much more seriously.
Carlos Huante actually goes over his own take on this in one of his YouTube videos exploring his work on Prometheus
. His idea was that the spores were tiny-organisms, resembling gnats, that would cover the explorers' visors like a fine powder. When they brush their hands across the visor to clear their vision they unwittingly crush them, releasing their acid blood, which slowly eats through the helmet and allows other spores to get in and infect them.
That sounds like an infinitely preferable idea to me.
As for Oram. I'm just at a loss. There's nothing I find credible about his actions in that scene. It's just bad writing.