I'm not so worried about the standard characters - sure, they'll pretty much auto-fail their first damage save (he will be doing at least 36 damage literally 9 times out of 10 - that's a damage save of 29) and every damage save after that - but I usually put between tough I and tough III on most combat NPCs.
The problem with adding tough is that it slows everyone down by the same rate. He's still outshining everyone but now you're slowing down the game. There's nothing wrong with putting tough III on NPC's but you have plenty of other tools to work with too.
My worry is special NPCs, who are supposed to be scenic and memorable, going down in two rounds. Even with tough and DR, unless I specifically nerf his character, that's 60+ damage per round.
If he's doing 60+ damage a round, he's nearly always hitting. Consider bumping the Defense of your NPC's by 3 or 4 grades. Soldiery types are probably batting at +2 to +4 better to hit than he at level 7 so they should still be hitting most of the time while he's closer to 50%. If you'd rather not do that, allow your soldier to build around All out Attack. +4 to +8 damage per attack should go a long way towards equalizing damage output.
Tho admittedly, there will be fights were he is near useless, and anytime he fights intelligent opponents, he'll get ganked, number one target.
Even animals are going to move to avoid being flanked when it comes with that level of pain. The only NPC's likely to simply stand and take it might be constructs, elementals, and undead, two of which are immune to his shenanigans.
Personally, I'd let the wookie win 1/4 of the time. 1/4 of the time, I'd structure the fights so that there are hard shutdowns available (types and qualities immune to sneak attack or flanking) so that he can't dominate the fight. The remaining fights I'd put in situational qualities that might come into play and require some level of thinking and or teamwork to get around.