"The fact that the Russian president has invited the Finnish head of state and Hungarian prime minister, but not the Estonian head of state, to a Finno-Ugric festival in the Mordovian republic next week should be a clear signal to our partners in the European Union to turn down the invitation," Mr Mihkelson wrote in his blog, according to [the Baltic News Service].
Mr Mihkelson feels the Finnish and Hungarian leaders would undermine EU solidarity if they attended without the Estonian president.
"The Russian president has of course purposely left the Estonian president out of the list of invitees to see whether a wedge could be driven between Finland and Hungary and Tallinn."
The blog article is here in its entirety (ee). I don't understand Estonian with any reliability, so I'll comment only on the translated bits and pieces.
Undoubtedly Russia treats Finnish leaders differently than Estonian leaders and this festival invite is yet another sign of it. Nevertheless, it's difficult to see how the visit hurts Estonia. Consider what will happen. Will Halonen and Putin put out a joint statement to the effect that Estonians should never have moved that damn statue? Hardly. Will Halonen promise to support Russia against Estonia's interests inside the EU? I consider it unlikely. Halonen and Putin will probably discuss some bilateral issues between Finland and Russia. Halonen will say something suitably considered to express her concern over the treatment of Finno-Ugric minorities in Russia and Putin will give a bland response. The only effect all of it will have is that maybe, if we're lucky, the Mordvins and Mari will feel like they have friends abroad - friends who can't do much of anything to help them, but friends nevertheless.
As for EU solidarity, my understanding of the concept is that it's supposed to mainly apply in EU decision making, not in the bilateral relations between members and non-members. It can't really mean that if one EU country has poor relations with some country outside the EU, everyone is supposed to follow suit. To pick a hypothetical example, let's say that some leftist foreign minister with a peace sign on his lapel and a scraggly beard offends the Americans so that they refuse to have high level meetings with said lefty's bosses. Does that mean that Estonian leaders should refrain from meeting with Americans? I don't think so. You might argue that this is different because in some sense the Estonians should have been invited to tag along, but as far as I can see, there isn't a practical difference between attending this festival and any old meeting.