A lot of people are suspicious of the husband. Personally, I am not. The argument was recorded (we don't know how... phone, security camera, etc), so LE knows what it was about, heard both men's voices, and the time it occurred. Soon after, the husband called 911. He told TG he'd called 911. The very next minute (and I think during the 911 call), the Blink camera footage shows who is likely TG running from the house heading south (toward their barn/outbuilding/cropland), and he turns off his phone at the same time. The direction he ran makes some sense if we consider he didn't want to talk to LE.
LE arrives about 15 minutes later, talks to the husband, looks for TG, determines a crime has not been committed, and leaves. This is all from LE's own timeline.
LE has accounted for TG all that day and all the way through the 911 call. He's even likely seen leaving the scene.
So that means the only opportunity for the husband to have done anything to TG was in the 15 minutes before LE arrived. He knew LE was on their way, because he had made the call. How did he know if they'd be 15 minutes, or 2 minutes? Did he hang up with 911, find TG, hurt him, hide the body, hide any evidence, and do it all while knowing LE could pull up at any moment?
The very fact that the husband initiated the 911 call suggests, to me, that the argument was getting out of hand and perhaps it was the husband who felt threatened. That idea itself lends to questions about TG's state of mind at the time, IMO. We don't know any more than this, but LE definitely does, and they have said all along that the husband is not a person of interest. Jmo.