I can see the argument that yields on Scotland-LHR are certainly not what they used to be 10-20 years ago (when it cost hundreds of pounds for seat) due to the effects of the locos competing for the point to point traffic. As a result you could maybe create an argument for canning services if you just look at that element. However, these flights are important for LHR feed and what I can't really see is BD (and by extension LH and the rest of STAR) completly abandoning the whole W of Scoland market in terms of connections.
I would imagine a fair few STAR airlines at LHR (with maybe 1 or 2 in particular i.e AC?) get decent feeds from BD at GLA. It's all very well saying that alternative LH services to feed pax through FRA could be brought in, but how possible is that before FRA's new runway opens? ERJs to BRU - not much capacity. GLA management are almost certainly after these services anyway but don't seem to have been succesful in chatting up BD thus far!
Whilst on the subject of BD at GLA, why do regional persist with their GLA and EDI-LBA services when pax numbers appear to have dropped off over the last few years with loads looking about 30-40%? Presumably a few people are paying through the nose to get to LBA? I would've thought sending the GLA ERJ to somewhere like BRU or FRA twice daily may have attracted more pax (at still reasonably high fares).
Re GLA-LHR, whilst there are some questions re the OP given their posting status, at the end of the day this is a rumour forum so even if they are misinformed I don't think it's necessarily fair to accuse them of making things up.