Thats not to say he's no good - the point is it's easy to counter when you know the strategy.
Ah you say but he should be able to blend with my counter into something else.
We are talking about teacher and his/her students - are we?
And: In our training it's normal to "test" the techniques of our partners by resisting or cuntering them.
When I begann to do Aikido I admired my teacher for the ability to do the techniques he wanted to do with every student. If he wanted to do irimi nage you could do nothing against that. Neither beginners nor advanced students could resist to his technique.
By now I am teaching aikido myself. And I think it is a matter of course that I can do the techniques on my students even if they try to resist.
Because a teacher should be able to blend with a counter of a student and find a way into and through the technique he wants to demonstrate. Or he shouldn't call himself a teacher.
The more difficult this becomes because of the skills of a student the more I become the partner of that aikidoka instead of being his teacher.
And - how Szczepan Janczuk wrote - everytime a student is able to resist or counter my technique this is an opportunity for me to learn and to improve.
Or at least hope I do...