Hello,
Late to the party - BETT seems a long time ago now, but...
Yes, Moodle (when put together by Atomwide as part of their Learning Platform) met 100% of the technical standards, but I'm pretty sure this involved a fair bit of work by Atomwide, who have applied to be Moodle partners but aren't as it seems the process is oh so lonnng. It wasn't just Moodle, but (afaik) Moodle was the core component of this.
The specifics of why Atomwide aren't on the Framework for LPs are, as suggested above, nothing to do with the software.
Also bear in mind that, as Becta will tell you time and again, the Framework isn't about supplying specific pieces of software, it's about providing services and then using the software to enable those services to happen. Hence why Moodle can be supplied by RM if they were a school's / LA's suppliers through the framework and the school/LA insisted on Moodle. The blog post cited above explains some of this...
Ian.