The Racing 92 stand-off was dismissed by referee Wayne Barnes following a TMO review after catching France full-back Brice Dulin in the neck.
While there was no malice in the challenge the fact it was contact with the neck, with force and without mitigation, meant Russell was sent packing.
Former France hooker Kayser, summarising on BBC One’s coverage, felt Dulin had left himself open to the challenge.
He said: “I think it’s completely accidental, but Dulin also went in high with the tackle – he could have gone for the legs. He exposed himself.”
Paterson, who won 109 caps for Scotland, added: “The only deliberation is, where is the point of contact?
"Finn’s elbow was certainly on the chest but further up the hand was close to the neck. Its just instinct; it's not foul play.”