Not convincing, again it depends on your interpretation. No facts just assumptions of his intentions or motivations. This is going nowhere, we can waste time arguing our point of view on the matter, but it's nothing but a speculation. There has bever been a vampire ascendant, there is no precedent. Unless the developers/writers clarify the issue.

I think they should add a choice to a conversation for two of you to stay together as you are (Tav/DU). Especially being a DU Bhaal spawn doesn't make much sense to become a vampire spawn at all.