It's not as relevant if it only applies to one subtype of vampire and a single Silven muter. It states all types of enslavement and mind control, which there still isn't a whole lot of. Even if Vampire versus vampire conflicts might become relevant it's only against Alais which need to kiss you for it to work. I don't know how other people play their characters, but I don't usually kiss people mid fight or that may be a threat and with sanguinology I can know 'just be careful and don't kiss any fellow vampires or random people you don't trust and you're okay'. Thus really only limiting it to mindlock muter which is very niche. Slizzar can easily just bypass it as well, so in my opinion it seems like it's a little too niche now, even if you're hoping for it get more relevant if the vampire community increases in number. I just think it seems like kind of a waste of a mutation now since it's really specific and can be easily bypassed. That's my observation of it, as most vampires won't be strictly fighting against one single type of enemy.

My issue summed up is this: If it's so easily worked around in multiple directions, why have it there? I feel like it should be changed and/or broadened so that it becomes more relevant and useful. An ability isn't as appealing for usage or character development if it applies to one very specific niche, especially if you have to hope it becomes more relevant over time based on uncertain circumstances.