You’re right, Boris Tadich is a sell-out milquetoast (and happily his popularity is plummeting since Serbs are realizing that he’s the traitor he is).
I think that’s why these ad-hoc organizations were reaching out first and foremost to Serbs in Britain, Canada, Australia and USA to come and start Kosovo churches, videotape any Kosovar (or NATO soldier) atrocities— since they’re in other countries, technically these Serbs are acting on their own (and not at the behest of Tadich or anyone else *within* Serbia). And as Serb citizens, on the basis of UN Resolution 1244, they have every right to move into Kosovo and establish churches.
Moreover, there is not a single international authority that has recognized Kosovo. 75% of the UN (and almost all the big countries) never will, and the split within the EU means even the EU doesn’t recognize it. Heck, even the “have-recognized” countries are having second thoughts— the recent EU resolution to push the non-recognizers to recognize Kosovo (a resolution forwarded by Dhimmi Britain, the most anti-Christian, Serb-hating country in Europe) backfired horrendously on the Brits. The British expected near unanimity, instead it was a split vote as other countries caught onto the problems of having a Muslim narco-state right within Europe, which actually bolstered the case of Spain and other non-recognizers. Also, Dhimmi Britain is bankrupt and literally splitting apart, so they’re impotent to do anything.
This really all boils down to whoever’s motivated enough. If overseas Serbs start up churches in Kosovo, they’re doing something peaceful (albeit with armed guards as needed) and within their rights as Serbs in a Serb region entitled to freedom of religion. There’s absolutely nothing that NATO or Dhimmi Britain could do about it.
And yeah, the NATO and Dhimmi British soldiers might try to harass the Serbs, maybe close down a church here and there but so what? The Serbs merely need to stay patient and motivated, and wait the NATO troops and Dhimmi British out. If they try to close down or block a church in one place, the Serbs will just construct another. Then if NATO and the Dhimmi British try to close it down, they’ll just cause a reaction, get the Serbs to film the church-hating troops on video, cause them international humiliation and gradually wear them down. That’s the key advantage for the Serbs here— NATO and the Dhimmi British are bankrupt and have little interest in a prolonged Kosovo occupation, whereas since it’s the Serb homeland, the Serbs will never leave. If pushed around, they’ll just push back and come back stronger again.
And since Thaci's thugs refused to issue such a permission, and Serbia refused to ask for one, the end result was that the Serbian minister, despite tough talk, never realized his visit.
So, while in theory he could, in reality he couldn't. Force can only be met with force. That doesn't have to be brute force, but it has to be compelling. And when it comes to force, Serbia has very few realistic options. The only one that could have an effect would be a mass Gandi-like takeover of Kosovo by 5 million Serbs willing to relocate and simply march into the province. But the Serbs lack the willpower to do this.
Tadich's government, of course, is in no mood to really challenge anyone but only to provide a strong nationalist show for domestic consumption and to appear "European" at the same time.
Serbia's liberal elite, like those surrounding another Boris (Yeltsin), believe that Sebia is a for sale geographic location on the European map that only needs to be cleansed thoroughly and recast into something it never was (and never will be, because cultures don't mix, especially if they are bad imitations).
Unfortunately, with the help of about 15-20% non-Serb minorities (not counting another 20% Albanians in Kosovo), and another 10-15% of outright serbophobes among ethnic Serbs, Tadich and his ilk are not too worried about being forced to call new elections any time soon.
They will continue to prance around pretending they are doing everything possible with diplomatic means (which are useless because the sole superpower does not follow international rules) while quietly allowing the situation to deteriorate further to Serbia's peril. The focus is now on alienating Voyvodina legally and politically and creating conditions for the eventual dismemberment of Serbia to essentially the old Turkish pashaluk.
Tadich and his friends are the tools for such a reconstruction work. In the end, Serbia will be just another vassal dhimmi statelet always kept in check by governments that are ultimately serving someone other than the people they supposedly represent. If you lack the resolve, and the Serbs have no resolve to discipline themselves, and are willing to let the river carry them, they will never get to the other side; just where the river takes them.