My group's interpretation of the spell is that it literally prevents the passage of anything, including all spells, in the manner that I described in my post. I was assuming that this was the default understanding of how the two spells worked. Perhaps I was wrong. If so, then the DM really has NO grounds to be claiming that he can't touch touch the Psion and that the combo is overpowered. See, there's this spell called Acid Fog, and this other one called Mind Fog. And there's that spell that allows you to summon creatures, even on the other side of walls of force. Oh yeah, and don't forget Cloud Kill and Destruction. If the telekinetic sphere only blocks spells that require line of effect and physical movement there are SO MANY OPTIONS, even at low levels.
Oh wait, I see what you're saying. You're interpreting the description of wall of force to imply that a Wall of Force blocks all spells, even those that don't require line of effect? Weird. I don't think our group ever used Wall of Force like that. We only had it block line of effect spells, since allowing it to block line of sight spells never made much sense to us. If that's the case, I can understand your argument.