Udis are close to Eastern Armenians and vice versa. But Udis are a complete outlier in Nakh Daghestani family. In the top 20 ethnicities there is no single NEC nation close to them.
The first picture is from Dodecad, the second one is from G25. Notice we don't have yet Eastern Armenians in G25, but when we will have them they will be the closest. (see the update )
The historic reasons of this proximity are quite long to describe. But they are other reasons like the drop of population size which increase the instability of the population DNA.
When the effective size of a pop drops below a certain level it's Y dna becomes very volatile and prone to extreme drift. One such a classic case are Basques who's Y dna say nothing about their origins. The same can be true about Udis though in this case I am expecting some conservatism.
Here is the Y dna of general Silikyan (Silikov) who's patrilineal side has Udi origin. Yet the Y dna has European origin.
Anyway only ancient DNA will help to understand better this situation.
PS. An update. The third image is the distance in G25 after the addition of new Armenian_Syunik sample.