Rob, I think you are mostly right. There are some coins that are difficult to evaluate as the presentation may occasionally surpass the ability to enumerate. This coin in hand is such a coin and really wish I could share it independent of my ownership just so that people could appreciate it. Another such coin that I do not own is the [graded MS67] 1850 half crown that looks nearly a proof. Another such is the 1839 currency half crown that I think you know, now in an MS 64 PCGS slab. How to grade it, or these other two? Another is that mentioned 1920 specimen half crown. And on and on....
I think a lot of the issues arise from a lack of familiarity with the subject matter. The paucity of slabbed examples for many types, particularly the esoteric, tells me that they have relatively little experience with some of the rarer pieces. All the above pieces would fall into that category. In a worst case example, a unique coin with a unique design means you have no reference point. The same could also be said for the many types where there is only a single slabbed example, albeit of what is a relatively common coin. Just as I wouldn't expect to grade US coins to a given slab number without a level of experience, they are probably in the same boat with many foreign issues. I have a few Peck 1053 pattern halfpennies and the grading on them was all over the place just as with the above pieces. Then there is my formerly 65 slabbed 1673 1/2d which was actually 1675/3/2 (they couldn't even get the date right), or my 1721 halfpenny that was in a 65 slab, but when I took it out found a significant flaw in the edge, which according to previous posts should have been downgraded for that, being a defect, after all, most of the laminating flan Victorian decimal patterns appear consistently with a 63 label. And best not get me started on 64 Cameo patterns that should be in an unc details (repaired) slab or similar. I appreciate there is supposed to be a set of rules, but it doesn't explain why they seemingly fail to stick to them so frequently.
AFIK, they will occasionally send GB coins to GB for experts to look at. However, I know of an instance where they did NOT take the advice of the expert on a 20th Century rarity and went against him (have to keep that one confidential).
I wouldn't dare give any opinion of a grade on a coin picture like this. It looks to be a phone picture, of a picture on a computer monitor...I can see pixelation from the computer monitor. Nonetheless, I don't see any obvious reason why it should be in a PF63 holder, but I didn't see the coin in hand - and those pictures aren't doing us any favors in viewing the actual surfaces of the coin for things such as hairlines, etc.
Of course that is always the way out, and I agree: seeing it in hand. Since that is not our medium for viewing, then perhaps referring to it by the PCGS coin number on their GB census page, it is #504887 and the first pictured. And though it means nought evidently, I just described the fact that neither Steve Hill, or Mark Rasmussen or I found any hairlines on a very near to FDC coin - which is why I bought it as well as it being from the Baldwin's basement prior to their move. I have seen the Monaco coin just sold, which has a bit more colour but does not outpace this coin in strike or cameo or wear and has similar very small oxidation spots on original uncleaned flans.
I believe you, but what are we supposed to do for you on a coin hobby forum? You know the series, the two guys you mention know the series, and we believe your assessment - but besides lamenting that no one will listen to you at PCGS I’m not sure what you want to hear. Send it to NGC? Then cross to PCGS if you “need” it in PCGS plastic? It’s clearly a nice coin.
You are quite right, and eventually I may have to if it is to come for sale. At one time it was not as important. The Monaco coin went for 50k Euros, possibly plus commission! That was obscene money even for a beautiful coin, however I guess that is the new normal.