Justification isn't part of this thread; just the rules.If you're forced to use the squeezing rules you can enter, but not go through unless you render the opponent helpless while you're there. Very small creatures can go through.Ending Your Movement
You can’t end your movement in the same square as another creature unless it is helpless.
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Very Small Creature
A Fine, Diminutive, or Tiny creature can move into or through an occupied square. The creature provokes attacks of opportunity when doing so.
The Tumble skill lets you go through and also avoid AoOs.