That would be wrong. He already killed a cousin in the second season, which is bad enough.
You can strangle someone with one hand, it's not like it takes a tremendous amount of force to put enough pressure on the neck.
You have not really offered any concrete reason as to why Euron would be the one to kill her other than saying that the signs point to it...what signs? He had three scenes in season six, and the last we saw of him was ordering his followers to build a thousand ships (which in and of itself is a nigh-impossible feat considering several factors). That's all we have seen of him, yet you claim that he will be the one to strangle her when it is considerably more likely that it will be Jaime if you consider the factors that I have pointed out to you.