I don't buy that at all.
Martin Tyler's loyalties IMHO lie with Sky TV and whatever angle they are pushing. Tyler is highly experienced and knew instinctively and immediately that the Aguero winner - a last minute goal to clinch a title from our fiercest rivals when 3 minutes before we had been 2 goals away - would go down in the hall of greatest PL moments - as indeed it has done. In terms of the Sky TV 'we bring you all the action from the most dramatic league in the world' narrative, Aguero was toeing the line even more closely than Tyler.
So if you want evidence of Martin Tyler's views on City, look elsewhere.
Many have mentioned the difference between the commentary on Liverpool's goals and ours when they beat us 3-2 the season before last. I would go to another game, the Old Trafford derby a few weeks before that game. In particular Dzeko's first goal. Most will remember he scored after about 45 seconds. You can imagine how bananas Tyler would normally go if the away team scores very early on in a fiercely contested local Derby.
When Dzeko scored you would have been forgiven for thinking that his microphone wasn't working properly.