That sounds like yet more of the usual sensationalism in the PT/UK press war to me.
Once the original team got booted, the PJ seem to have been doing their best to avoid leaks. However, the PT press were the first to publish the Euclides story. That was then picked up by the UK, which went further by publishing the guy's name. Personally, I find that reprehensible on many levels.
I wouldn't be surprised if dealing with the media was an agenda topic at a joint meeting, but neither the Met nor the PJ can control their tabloids, particularly in an international investigation.
It may well be that the two teams are focusing on different leads / aspects to a certain extent. If legal considerations mean that they can't form a JIT, then they will have to continue separately, with common areas of cooperation.
Trying to build footballesque antagonistic hysteria isn't helpful to either police force, nor - more importantly - to Madeleine.