I get they use Venom series naming for marketing since the line is successful for the most part. But it's not the same core... I guess 900G did this with the Badger line also, but I also questioned that naming convention/series choice as well.
Motiv has done this several times now, and I agree, should be a different line. Hammer did it with the Black Widow line(only once if I recall).
Motiv had the Primal TV4, which used the Thrust Core, but the Primal Impulse had a completely different core shape which is still being used in the Primal series today.
They also did it with the Forza line with the original Forza, Forza Redline and Forza GT having the same core, then the Forza SS used the Sigma core. Seems to me that makes it NOT a Forza.