Yes, because goals conceded are definitely the sole responsibility of the keeper, and not the defenders in front of him; nor the midfielders who lose the ball when too far up the pitch.
And this is the classic tactic in defending the indefensible: I am right because I'm believe I'm right, and no amount of reasoned, factual argument will change my mind.
Don't know about the reliability of the original source, but the fact that the one player pictured isn't a Saints player any more doesn't fill me with confidence.
Mbeumo was 19 (just) when he signed for Brentford too. I'd like to think anyone of that age scoring 15 goals in their first season would be regarded pretty well.