This is good advice and also correct - it's really not easy to believe that the dog is acting up because he's nervous, but from his behavior it was plainly clear that he was. Once I saw someone else confirming that the behavior was anxiety-based and that we needed to reassert consequences and rewards, we really didn't need much professional help.Actually work with many dogs that have been to a behaviorist and failed.
The recommendation was to AVOID a behaviorist - and I offered a referral which I was never solicited for. I'm not going to speculate why but I would imagine the second someone says "take charge" the need for professional help is reduced significantly.
Breed is irrelevant on this one in my experience with many many resource guarding dogs - I've seen it in everything from labs to pitbulls to bichon frise - it's a nerve thing - anxiety and fear based - it's not a "dominance" issue in any of my experience or a breed issue.
"taking charge" may help - all the way around but it needs to be done carefully and be well understood by the dog. The dog has shown a willingness to be aggressive. Inconsistent and confusing punishment could lead to a big problem. There needs to be good balance. The dog's world needs to become black and white 24/7/365. The guarding might then go away without being addressed directly. Often times it won't though. So a good strategy to keep everyone safe until it's solved is also in order.
The issue had also been confused a little by our vet, who told us that we should just let him be, avoid confronting him, and wait it out until he got distracted. Our chessie is not one to get distracted. That was terrible advice.