I have heard of inspectors climbing up an antenna tower to get onto the roof.  I have done that myself but I was much younger than.  I'm not sure if I am wiser now or if I just scare easier.
At a recent inspection near Brampton, I saw a good reason why not to climb up the antenna tower. I was on the roof of a two storey house, (I got there using a ladder) and saw that the tower was wired to two lag bolts in the fascia board.  
Technically antenna towers are not part of home inspection and I didn't actually inspect the tower. I inspected the way it was fastened to the house.  I don't inspect fences either but if a fence post is fastened to the house I do try to determine if the way it is fastened can cause a problem.
This antenna tower would likely not cause a problem to the house but a 30' tower coming loose and falling could do some damage to someone working in the yard.  An ounce of prevention here is worth more than a pound of cure.