I think you're making the right decision to pass on taking this steer home to raise out. I wouldn't give him more than 30 seconds to have been out of your electric fence, and that's being generous. Ours are always pushing each other through 6 strand barbed wire when they get to pushing each other around next to a fence line. Cows (my generic all gender term for cattle) have a freight train mentality when they get startled, pushed, or just plain bull headed (there is a reason that term is what it is). They'll go through whatever to get where ever they want to be. I worked at a stock yards for a while and one of the cows being sold was so worked up and crazed that when she came off the auction block, she busted through 5 different pens, tore down 4 heavy duty bull gates and went on a rampage throughout the sale barn property. Just in the last couple of months here, I've been chased by a cow who just calved, stuck between two bulls who decided that while I was walking out to feed was THE time they wanted to tussle with each other, nailed from behind by the psycho cow we have here, and hooked a glancing blow off the face (thank god) by one of the horned cows going for another one. I still enjoy them, but they deserve respect and they can be a lot of work. I can see why the seller may not be very pleased having to hold your steer or possibly loosing the sale, but perhaps you can offer to cover his time/expense for castrating the bull? I'm sure deep down though he can empathize with what your fears are. Cows and horses while alike in a lot of ways are different in that a horse won't generally run through you just because he can. You can't be afraid of cows or they'll make hoof tread out of you.