Biased Introduction

I listened to a short debate between Glenn Reynolds of Instapundit and a woman from Politico.  When Julian Marshall of the BBC introduced his two guests, he labeled Glenn as 'right-leaning' but offered no such label for Heather from Politico.  Before either person has said a word, it has already been established that Glenn is biased and Heather is not.  This is not accidental.  Though Politico is viewed as relatively unbiased in the Republican vs. Democrat axis, it is immensely biased in the establishment vs. outsider axis.  Politico is all about the insiders, the palace intrigue, the parliamentary plots.  How might the audience have reacted if Marshall had instead labeled Instapundit as outsider-leaning and the Politico as insider-leaning?  Now the biases of each are revealed.  That he didn't do so reveals his bias.