You told them they should talk to some life sciences graduates. They relayed that they knew several such people. And now you're telling them the experiment you proposed is anecdotal and not meaningful, seemingly because it didn't produce the result you wanted.

Another approach would have been to say, "interesting, my experience differs," and then to compare notes.

For instance, is it the case that you're a software engineer who occasionally meets people who've pivoted into software engineering from life sciences? That could be a very different sample than someone who's spouse has successfully gained traction in the field. Seems likely to me that there's something to be learned from both perspectives here.