Some situations in which you LOSE you Reflex Save:
1. Dex of "0" "DEX 0 means that the character cannot move at all. He stands motionless, rigid, and helpless." It does not say it quite directly, but obviously you get no Reflex save if you cannot move.
2. Any other stat of "0" - creates a condition of "Death" (Con) or "Helpless."
3. Helpless "...In fact, his Dexterity score is treated as if it were 0... "
4. No room to evade: "As with a Reflex save for any creature, a character must have room to move in order to evade. A bound character or one in a completely restrictive area (crawling through a 2 1/2 foot-wide shaft, for example) cannot use evasion."
Some situations in which you KEEP your Reflex Save:
1. Grappled: "Engaged in wrestling or some other form of hand-to-hand struggle with one or more attackers. A grappled character cannot move, cast a spell, fire a missile, or undertake any action more complicated than making a barehanded attack, attacking with a Small weapon, or attempting to break free from the opponent. In addition, grappled characters do not threaten any area and lose any Dexterity bonuses to AC against opponents they aren't grappling."
2. Pinned: "Held immobile (but not helpless) in a grapple. "
3. Prone: "The character is on the ground. He suffers a -4 penalty on melee attack rolls, and the only ranged weapon he can effectively use is a crossbow, which he may use without penalty. Opponents receive +4 bonuses on melee attack against him but -4 penalties on ranged attacks. Standing up is a move-equivalent action."
Putting all that together, it seems that the intent of the rules of Reflex Saves is that you only lose them when you are really quite restricted in your movements - more than simply two of you in a 5-foot square.
So when would you lose them?
Let's try and make up a couple of examples:
4 medium characters in a 5-foot square with no room outside that square (like a 5-foot square room).
Crawling though a 2-1/2 foot wide shaft (note that you cannot dodge because there is nowhere to go and you've got walls all around you).
Tied up (as in a bound prisoner).
It appears that someone holding you is NOT enough to prevent your save - if that's true, then two characters standing in a 5-foot square will not deny your save.
As far as combat restriction of more than one character in a 5-foot square, well, there are plenty of times when there are combat restrictions that do not affect your Reflex Save. There are quite a few examples in the Condition Summary list - look at how often you lose your Dex bonus for a condition that does not deny your Reflex Save.
So, Kreynolds, you logic is quite weak here. Perhaps you have a better argument you have not yet put forward?