Here's what Robert's Rules says:
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2. All bets must be at least equal to the minimum bring-in, unless the player is going all-in. (A straddle bet sets a new minimum bring-in, and is not treated as a raise.)

3. All raises must be equal to or greater than the size of the previous bet or raise on that betting round, except for an all-in wager. A player who has already checked or called may not subsequently raise an all-in bet that is less than the full size of the last bet or raise. (The half-the-size rule for reopening the betting is for limit poker only.)

4. “Completing the bet” is a limit poker wager type only, not allowed at big-bet poker. For example, if a player bets $100 and the next player goes all-in for $140, a player wishing to raise must make the total bet at least $240 (unless going all-in).

5. Multiple all-in wagers, each of an amount too small to qualify as a raise, still act as a raise and reopen the betting if the resulting wager size to a player qualifies as a raise.

Example: Player A bets $100 and Player B raises $100 more, making the total bet $200. If Player C goes all in for less than $300 total (not a full $100 raise), and Player A calls, then Player B has no option to raise again, because he wasn't fully raised. (Player A could have raised, because Player B raised.)

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Therefore, SB cannot reraise here.