Quarians don't have insects on their planet so they naturally did all the pollinating themselves. BioWare clearly put some love into the Mass Effect Legendary edition, with a host of small changes included for the biggest of Mass Effect fans. This could, as Adeese mentions in his answer, mean that one Quarian is not enough to extrapolate a face for 'any Quarian' personally, though, I took it to mean that you thought well enough of Tali that you did not associate her with the Quarians willing to commit genocide on the Geth. What comes to Tali, I'm really bummed Bioware didn't pull off their original idea of making Tali really adorable, but then revealing her very alien face like their originally planned. Mass Effect remaster gives Tali a new face. According to Murgatroid99 in the comments below, the line is something close to : 'Then your memories of that Quarian do not map to our historical data'. and youre left without any idea how Quarians and Tali look like.which gives mixed. When I answered that I had indeed seen one Quarian unmasked, Legion replied with something along the lines of 'then you must not associate that Quarian with the ones you are seeing'. During Mass Effect 2, a character, Tali, will take her mask off. I however contend that this is NOT a plot hole : Shepard commented upon this fact, with his guide (Legion, in my case) asking if he had ever seen a Quarian without his mask. Playing through the game with my own ME2 save where I romanced Tali, the scene still played out as you described (with masked Quarians). Adding my own answer since none of the others feel entirely correct to me )

Mass effect tali no mask