1/ yes there was suspicion. there is video of Arbery in a property and running away after he left.
2/ there are logged 911 calls on the day and a month earlier a gun was stolen. the guys who had the gun stolen chased after Arbery and confronted him. one of the guys had a shotgun, Arbery lunged at him and wrestled for the gun which went off 3 times killing Arbery.
the highlighted part of your post is incorrect.
Okay, let's talk about what reasonable suspicion means rather than some erroneous understanding.
Arbery (only confirmed afterwards) was witnessed in an unsecured property and leaving with no items. This would be suspicion of trespassing, not burglary.
There was a previous instance of a male, who resembled Arbery, entering a similar property and again leaving without taking any item. Police confirmed this.
So here's the big bit.... burglaries had been reported to be taking place, but please highlight any evidence to suggest that the offences were in any way linked.
Did Arbery have form for burglary? Did he match any description from those burglaries? Was there any evidence that a burglary had just took place?
Or is it merely okay to go... "
Aye, there's been burglaries taking place and we've seen a black man in an open, unsecured house taking no items, so it's him"?
Now here's the interesting part, there was evidence of many individuals entering the said unsecured properties before the incident, including white people.
Were they unlawfully confronted by a ground of men, armed with weapons, which led to a person dying? Unsurprisingly, no. But shouldn't that link have been made?
So we have a group of men making a citizens arrest based on nothing but insufficient evidence (I'm being kind there) and their racist prejudice.
Now, the threat to life part: could it not be argued that three armed men, confronting a man on his own and with no evidence of a firearm, would pose a threat?
Or I could just say that people defending these men clearly have an issue with a black man because he was black.
So why is a probation from 7 years ago relevant? Or a shoplifting charge? Why do they matter here?
I'd ask him whether those three men knew of said probation or charges otherwise it's completely irrelevant.