Honestly, Gustavain is so certain that Phillip won't be staying behind that he's a little surprised when he's not there at the docks to meet them. Obviously, there's no reason for someone as actually powerful as Phillip to not just head there, but it does very much blow their cover for him to be there and a known associate and all of that. It's less about the capability and more about the culpability of the whole thing-- but Gustavain also knows that Phillip has his own ways of figuring out how to get around all of that.

Maybe, on some level, there's a recognition of that in this moment. He's certainly been adjacent or the subject of enough assassination attempts to typically have a better guard, if nothing else. Adding to that, they're in public, technically, but this is a quieter spot, nowhere that guarantees privacy, but no immediate eyes to comment on a rare display of public affection in a city more known for intellectual pursuits-- or eyes to assist with a sudden knife to the ribs.

Maybe it's also just that he's not used to seeing male Viera at all, disarming enough to start with that it throws him just the moment long enough to get close. Whatever the reason, the "deathblow" is immediate-- as soon as the other man's mouth is on his, all resistance is futile, at least for the first few moments. The kiss is so sweet that he just gives way in his surprise, doesn't exactly kiss back but tilts his head instinctively, inviting, eyes gone momentarily wide easing closed before he can think to stop them.