But brother, I don't think سلالة in verse 21:12 means purest sperm. The verse says سلالة من طين meaning an extract of clay; that is to say, the creation of Prophet Adam (peace and blessings of Almighty Allah be upon him). And also, the word نطفة can be interpreted as zyogte. The Glorious Qur'an even says that man is created from a mixed sperm, which is basically the definition of a zygote.
إِنَّا خَلَقْنَا الْإِنسَانَ مِن نُّطْفَةٍ أَمْشَاجٍ نَّبْتَلِيهِ فَجَعَلْنَاهُ سَمِيعًا بَصِيرًا
Indeed, We created man from a sperm-drop mixture that We may try him; and We made him hearing and seeing.
Anyway, as a whole, Barak Allah Feek the article is amazing.