No worries, and that is a fair concern; I've not seen him mentioned on this site before. He is one of the many online influencers in the firearms world, similar to other online influencers like Hickok45, WhoTeeWho, Paul Harrel, and a handful of others. If memory serves, MrGunsNGear is also a former Army Ranger (but I'm not entirely sure). I have been following him on Facebook and YouTube for a number of years, and have found him to be a pretty credible authority. He posts reviews of all kinds of "guns and gear" a few times each week on his various social media channels; and usually includes affiliate links to various merchandise (although he is rarely the actual seller). In the case of this Garmin deal, the link for his website above is basically just an affiliate link that redirects to the actual product listing on Battlehawk Armory's website. I have bought from Battlehawk Armory twice in the past (each time was a bulk ammo purchase), and they seem to be pretty easy to deal with. I think you can do business with them with confidence.
In the meantime, I have received the email with my discount link for the Garmin, but have not completed the order yet. My discount link is good for the next 24 hours.