I did some experimenting with a no-reads based techchase. My conclusion is that I don't think it's possible. Here's why:
Fox and Falco have three really strong options. The first is tech in place→shine. The second is tech in place→spotdodge. The third is DI away from YL and tech roll away.
Tech in place happens really fast, 26 frames. In most tech chases, e.g. Sheik's, it is advised to prime yourself for the tech in place and grab that. If the tech in place doesn't happen, react to it not happening by chasing them. Sheik's grab is 7 frames, not 11 like YL's though, which is a big problem. DruggedFox is notorious for having perfect techchases with Sheik, but has noted several times how hard it is to react to tech in place. Because of this, I'm not sure it's humanly possible with YL's grab. Let's pretend it is...
YL actually has quite a few frames to act before Fox and Falco can get a shine out after tech in place. If you know they are going to tech in place, you can easily WD back→grab or dash back→pivot grab. Both of these avoid the shine. You only need to dash back for 9 frames (that includes 1 frame of turn). If Fox/Falco want to go the safe route, tech in place→spotdodge makes the window for reacting to tech in place the smallest.
There is a problem with WD'ing/dashing backwards though. If Fox or Falco DI the throw away from YL, they can tech roll away and YL will not be able to chase them quickly enough after a dash/WD back (which would have been done to avoid a shine). They can spotdodge (and possibly even roll (I didn't test it, but if the YL isn't frame perfect, they could probably get a roll off)) after the tech roll. YL could predict this of course, wait for their reaction, and then possibly punish. Buffered jump after the tech roll may be hard for YL to punish.
So what if YL doesn't dash/WD back to avoid the shine? He can definitely react in time to whatever direction they tech roll. He may not be able to react to tech in place, however, as said before.
I think the best bet is to wait after dthrow, prime yourself to react to tech in place, and try to get that reaction. If you see them tech roll, you have time to chase them. Basically, the same as Sheik's tech chase, but you have to react faster by 4 frames. If they get get tech in place→shine happy, call them out with a WD back or pivot grab. Falcon is basically the same except he doesn't have a shine. Tech in place→spotdodge is his best option, but he can mix it up with tech rolls to keep you honest.