The other two have to do with Blair himself.
First, his scoffing at international law and cuddling up to George Bush -- clearly a man with no love of internationalism -- should disqualify him for any prestigious position representing a group of countries. Indeed, a case could be made that he should be sent to The Hague to face war crime charges rather than Brussels to be feted. The war in Iraq was unwanted in Europe (including Britain), probably illegal and fought based on lies. He should not be rewarded for this.
Second, Blair the European was always a con. He promised much but delivered next to nothing. We are no closer -- indeed, may be further away -- from joining the euro than we were when he took office. Our role as a "third" power with France and Germany is laughable. Given the chance to lead Britain into Europe, he caved in and promised a referendum on the ill-fated EU constitution, knowing that Britons would have rejected it out of hand.
In short, he is not qualified for the job.
Now comes the main reason. The British people only need a small push to send the country out of the EU, a disastrous prospect for our economy, society and place in the world. It is not their fault -- they have been subject to decades of lies from newspapers and politicians stirring up false notions of nationalism. No one -- least of all supposedly pro-European politicians like Blair -- ever defends it. They tend, rather, to blame their own shortcomings on it.
So here is the prospect of an intensely divisive and in some areas despised man being touted for a leading position that is being created by a treaty that rightly or wrongly most Britons are suspicious of. The disgust is already palpable.
It would do untold damage to Briton's already shaky relationship with Europe and play directly into the hands of eurosceptic politicians ready to drum up the (false) spectre of Brussels undemocratically running British lives.
For the sake of Britain in Europe if nothing else, this should not be allowed to happen.