It’s kind of interesting, but of absolutely NO theological significance whatsoever.
It does point out the holes in the theories that some have raised about Mary, the Theotokos, having other children, which even the Early Church recognized as false.
All believing Christians receive the blood of Christ in the miracle of the Eucharist during mass. Accept Jesus as the Son of God, live according to God’s word and you will live forever in Heaven.
My interest in this topic is probably more historical than theological.
That said, if these Syriac Orthodox folks can really prove they are descended from cousins or other relatives of Jesus, it increases the likelihood that they may have valid oral traditions which could shed light on theological questions.
I am not saying that I would consider converting to their church, in such a case. As a confirmed Catholic, I would not. However, these people could very well possess traditional knowledge which might enrich my understanding of Scripture.