I've seen a lot of in people go in on Merlin over this letter, but as much as I slate them over a myriad of other things I don't believe it to be anti competition.
The concerns basically boil down to a worry that London Resort are potentially evading proper scrutiny by submitting some documents after the period for representations has ended. As mentioned, the main document they are concerned about is one was assessing the current leisure market in the UK. As an existing operator, that's bound to make reference to Merlin's own operations in the UK. I don't think it's anti competition for Merlin (and remember BALPPA who represent the industry in the UK as a whole) to want themselves and others to have proper time to review and make representations based on the information put forward.
The term "anti competition" is to unlawfully suppress competition. That's a bold claim to make at the moment, as they are merely questioning that the correct processes and procedure are used. You could argue the reverse be true in that London Resort are being anti competitive by submitting such a document later to prevent valid concerns being raised.
Let's say I owned a takeaway and one of the same type was setting up next door. The planning documents were put through, and as annoyed as I am about it there's nothing in those documents that give me any cause for concern. The planning drags on as the building is listed, but the council allow for some time to allow for some further drawings to be submitted. Six months down the line they submit that info along with another document that has nothing to do with the listed building, but about the current takeaway market in the area. It's incorrectly saying I make a six figure sum of profit every year and there's a swell of surplus demand from customers in the area. The information is wrong, but I have no ability to argue against those claims as the period to do so has finished. That's a simplification, but that's what Merlin and BALPPA are getting at here.
Anti competition is not the same as a business wanting to protect their interests by ensuring everyone goes through the same planning process and procedure as they themselves would be subjected to. If something like London Resort got off the ground, it's right that all parties, be that Merlin, BALPPA members or the general public at large have all the information needed to assess the application at the correct time and have the necessary period to review and comment on it.