That quite dates back to 2001 and was as a part of liaison with the home office
The UKPSF are not the law, however are the recognised representatives of paintball by the home office, and usually talk in line with how the home office interprets the law
The general line of thought is that full auto and burst fire are not explicitly illegal, and therefore legal, however insurance policies for sites (whether UKPSF or not) do not normally allow for full auto / burst fire
This is mostly in regard to safety
A site can decide to allow full auto, but to get insured and licenced by the local council to run a site as a business they must produce risk assessments - so would need to show controls to cover the risk
I believe for international tournaments in the uk full auto has been allowed for events. The safety controls that can be placed on teams in a controlled environment is different then a walkon group on an average site