his ult is about positioning yourself with the two little walls he has there, unlike the enemy which has only one and doesnt know where ur gonna peek from
Ult wherever the sentinel is and walk into site. No defensive util and in most cases it will be 4v1 because most of the time a team won't be playing three on a site.
Iso ult is like a weaker version of phoenix's since you can get at most 1 kill but it's useful for stalling in post-plant situation or countering sustained ult like viper, sova, raze, kayo
i think honestly it's strong for execs cus u can take one of the site players just off the map when u have one in just tell ur team to exec and they either have a free site or a 1v4 imo