Slicing the pie is an exercise most easily done in real life when you only have one corner to "slice". Or, you have someone else with you who can be responsible for covering the other corner ... or the
really close next opposite corner, just inside the opposite corner you're having to pass while slicing the pie of
your primary corner.
Most architects don't seem to design their structures keeping in mind how easily they could be searched by LE.
In the limited bit of video clip, the deputy presumably couldn't know if someone was waiting/hiding around either corner as he "entered" through the "doorway" of the roll-up door, or whether someone might be waiting to ambush him from on top of whatever that cube structure was to his left ... or from around something on the opposite side of the huge space, higher up any stairs behind the camera's field-of-view, etc.
It can be more than a little daunting to try and search/clear a huge commercial structure containing separate areas, and the advantage is almost always going to go to the "hiding suspect", who only has to remain still and waiting.
Motionless is much harder to detect than something/one in motion, due to both stillness and probable lack of noise. In this case, the deputy might've been lucky, in one respect, that the armed suspect was both moving, and maybe making noise.
Yes, a suspect's malfunctioning firearm is always a tactical & situational advantage for the cop. Sometimes a suspect's gun experiencing a malfunction isn't discovered until examination of the gun, after it's become part of the evidence, though.
Something that can be pretty intimidating, and not a little scary, is when LE may put together training scenarios where the "responding cops" have to search structures for "suspects", and role players are used to wait to ambush them. I really liked K9's when they were available, but sometimes the circumstances of the particular situation mitigate against use of a dog, or something about it might be a policy problem, or if a K9 handler doesn't feel the dog can be properly utilized in that particular situation ... may put the burden back on the cop.