Have these 'PCN's' or lack thereoff been confirmed or denied by official BAA sources? Are you just guessing?
Yes, they are documented on the NATS site and I have had confirmation from BAA ops that they are correct and that these limitations apply.
I look at NCL and what I see are facilities deficient to what Edinburgh has, maybe Emirates did their homework and never ever Intended to serve Edinburgh, maybe their preferred option all these years has always been Glasgow, nothing sinister.
NCL may have a shorter runway and a smaller shopping mall, but it has much higher PCNs. This mean that a B773ER can depart with substantially more payload / range than it can from EDI. Operating from EDI, if ACN = PCN then a B773ER would be unlikely to reach Dubai with a full passenger load, even with a substantial tailwind and no cargo on board so it would either need to operate with a restricted passenger load or a fuel stop would be necessary. The ability to lift an extra 62,000lbs of fuel / payload from GLA or 69,000lbs from NCL was I imagine a significant factor in Emirates' deliberations.