True, because TWF doesn't have it to begin with.
Now a Tempest Ranger has to take:
Dodge
Mobility
Spring Attack
Leaving 4 Feats to Play around with (or 5 for a Human).
So let's take a Dwarf TWF Tempest Ranger with MBP as an example.
He can take TWD as well for a net AC bonus of +3 while TWF.
Now if he wants to throw on a shield for the +7 AC he loses bonuses for TWF and Tempest (or he should when it gets fixed), so a net AC gain of +4.
The max AC Bonus a Tempest Ranger Dwarf can get from the MBP is +18 (besides alchemical ritual) if he has a 28 Dex and DAM III.
MBP: +10 Armor +8 Dex =+18
Shield: +7
AC:+25
Without Shield: +3 from TWD and Tempest
So +21
Now the Fighter: let's assume what you said that since 22 Dex is easier that's what he has.
MFB: +13 armor + 6 Dex = +19
MTS: +9
AC:+28
That Fighter changing AC for Evasion has:
MBP: +16
Shield: +7
AC: +23
Yes he drops 5 AC for the use of Evasion, but only two less versus a HIGHER DEX RANGER who also wants shield usage.
If they have equal Dex they have equal AC while using a Reg Shield for AC and Evasion usage.
If they have equal Dex the Tempest Ranger has 2 or 3 more points of AC max than the Fighter while TWF.
Any Fighter who is AC minded will take Dodge so that cancels out.
They both can take CE so that cancels out.
And most S&B Fighters can probably squeeze in TWD if he wants, after taking SM, ISM, Dodge, CE, TWF, ITWF, GTWF, and TWD he still has 7, or 8 Feats if Human, to spend as he sees fit.
So taking TWD cancels out if the Fighter feels like it, leaving the Tempest TWF ahead by 2 points of AC if Both Fighter and Ranger have the same Dex while TWF.
They both can get Chaos Guards, so that cancels out.
They both can get Chattering Ring, so that cancels out.
The lucky Str-based 24 Dex Dwarf Tempest Ranger who also gets the +4 Dodge Bonus from Icy Rainments AND +8 Armor Bracers gets +12 +8 Dex=+20
2 more points of AC.
So:
MBP + Shield = +27
MBP TWF = +23