Its not the swedish that seem to care its the Danish.
I believe its something to do with the fact that the ATPL in the UK is a relatively simple procedure of get the hours do a sim check get the TRE to tick and sign and then send money in with the form.
The Scandi countrys its quite a bit more involved with a seperate sim session with an NAA TRE and aural exam and some more hoops. Also the year cost of maintaining licenses and ratings is significantly more than a UK license.
It seems the ATPL upgrade is a tidy little earner for the old boys club.
I don't think they have a leg to stand on with a JAR license but it all depends on how they have bought into JAR regs they may have differences filed.
They French can be a bit awkard as well with UK ATPL's flying F reg's commercially.
And being swedish and not having a swedish license might not be doing you any favours