huh? if you tech immediately they either inputed the clap or they didn't. You j.D if they did, run away if you didn't. If you mean they did drill arm special instead of clap than yeah, you should probably block. Heck you could just air dash forward and even if you do get hit by it, you'd just get knocked down, he'd get a j.B maybe, but he can't follow off of it because of its recovery. You could j.D it too, but... meh.
and i love killing neesan with 6c-shippu. It makes baiting gear's much easier and when you bait a gear, you can barrier block (or normal) till you're not blocking, take a step or two back (I usually do, dunno if it's required) and just shippu. You'll trade hits but he'll be receiving 4k and you'll get maybe 100. You can charge it a little if you want, but i'd be careful because he recovers before it disappears. Might mis-predict it.