I'm a little late to this discussion. I shouldn't be but I am still stunned that you got the kind of reaction from the breeders that you did. Any breeder touting perfection isn't telling the truth anymore than any human (since Jesus Christ) is perfect. And saying you somehow damaged a pup by having a stranger stare at the pup at that age should be a joke but obviously wasn't.
I've owned or handled several slow maturing breeds. Anyone who says having someone eye an 8 month old guardian breed is doing damage is just plain batty. That's life & they better be breeding dogs that can handle life or they're doing a disservice to their breed. My slowest maturing individual is my current guardian. She's darn near perfect now but as a pup, she should have came with a case of aspirin & barrels of alcohol. She was goofy. Only guardian I've ever raised that thought the couch was trying to kill her (because she stuck her head under it, raised up with the full couch on her head). So she ran off with the couch. No kidding. It was like living in a three ring circus & the clown was this goofy dog however at 5 months old, being with us less than 48 hours my husband saw something in the dog's eye. We had a visitor & he told the visitor to raise their hand up over their head. The person did. The pup went stock still. When he told them to do it again but this time the hand in a fist, the dog went from watchful & sharp to full on bear growl, a bark that rumbled the floor under my feet & my holding her collar feeling just how strongly she wanted to advance. This from a dog who would bump something with her nose & then bark like mad when if fell over. I nearly hurt my eyes from rolling them at this goofy dog but she'd fight to the death for my safety. Go figure. I'm thinking those breeders would want me locked up because I begin testing pups soon after they arrive at my house. I've a lifetime experience so I don't do this in big ways but little things like you did with your female are very good indicators. There is a chance that if you get a strong male who is more to your type of dog, the female might get in the game with a partner to work beside. She may not ever be as strong but then again, she might wake up & you have yourself a new dog. I have an old fashioned type Collie. She's the dog everyone assumes is a huggie cuddly dog. She looks it. She acts quite friendly. I have learned however her growing up with my guardian (a Giant Schnauzer) has taught her a few things. She doesn't have to be the guardian, she's the watch dog (alert dog) so long as the big black has the yard. The Giant is in charge. When the Collie has the yard, it's a different matter. She patrols that perimeter like a soldier. If you try to breach the fence or - heaven forbid - try to unlock the gate from the outside you could lose something you're rather fond of. The Collie looks sweet & cuddly but she's got teeth & the Giant's taught her well. She just prefers to work predator critters rather than humans.
So when you get your male, watch for signs that the female is catching on. Praise her for it when you see a spark. If my older dog is one I don't want the pup to emulate, then I don't allow them free time together alone. I have that pup grow up a little more independent. When he's old enough that he & I have the bond we need, he's obedient & answers to me... then I give him some time with the other dog & I supervise. So long as there's not an aggression issue between the two, this has served me well & saved me some headaches from the pup picking up bad habits.
I'll check back as I hope you'll soon have a pup that's to your liking & I'd love to know if he's helping the female grow into her job. Sometimes they can really surprise us.