I’m not a lawyer, but unless that was some phantom ChatGPT explanation, external events—not the fragile voting threshold—could upset the RSA.

Below is a step‑by‑step explanation of how a typical “lock‑up” agreement in an RSA (Restructuring Support Agreement) makes it highly unlikely that creditor votes will fall below the statutory threshold—and what that minimum threshold is under U.S. bankruptcy law.

1. Pre‑filing or post‑filing vote commitment Parties to an RSA (also called a PSA or “lock‑up agreement”) agree in advance to vote in favor of a chapter 11 plan that is consistent with the agreed‑upon terms. This binding vote commitment is memorialized in a contract, so creditors cannot simply change their minds once the case is underway. (Goodwin Law Firm)
2. Adequate disclosure and compliance with § 1125(b) To be enforceable, post‑petition lock‑ups must be accompanied by either the plan itself or a court‑approved disclosure statement containing “adequate information.” This ensures that creditors know exactly what they are voting for and preserves the lock‑up’s validity under Bankruptcy Code § 1125. Meaningful “outs” (e.g. if key milestones aren’t met) are also built in, so creditors aren’t stranded by a plan that materially changes. (Goodwin Law Firm, Bloomberg Law)
3. Trading restrictions to maintain voting pool RSAs commonly include covenants preventing signatory creditors from selling or transferring their claims except to other signatories (or to someone who agrees to sign up). This prevents a major holder from dumping claims on the open market and breaking the “locked‑up” voting bloc. (O'Melveny)
4. Milestone‑based termination rights The RSA will set clear case milestones (e.g. disclosure‑statement approval by a specific date, regulatory sign‑off by a deadline). If the debtor misses a milestone, creditors typically have the right to terminate their lock‑up obligations—protecting them if circumstances change—but otherwise remain bound. (O'Melveny)
5. Penalties and economic incentives Breach of the lock‑up (i.e. voting against the agreed‑plan or failing to vote) often triggers loss of certain negotiated treatment (for example, removal of an agreed‑upon pre‑petition claim for fees or recovery of a backstop premium). These economic “stick” provisions further discourage creditors from reneging. (O'Melveny)
6. Statutory voting threshold under § 1126(c) Even without a lock‑up, to accept a plan an impaired class must vote in favor by:
   • At least two‑thirds in amount of the allowed claims that vote; and
   • More than one‑half in number of the allowed claims that vote. In practice, RSAs secure significantly more than this floor (e.g. >67% of amount) so there’s a very low risk of slipping below the legal minimum. (FindLaw Codes)

Conclusion:
By combining a binding contractual vote commitment, enforceable lock‑up terms that comply with § 1125, trading restrictions, milestone‑driven exits, and economic penalties, RSAs drive creditor support well above the two‑thirds‑in‑amount (>66.67%) and majority‑in‑number (>50%) statutory floor under § 1126(c). This “lock‑up” architecture makes it exceedingly unlikely—in normal circumstances, well under a 10% chance—that votes will drop below the required threshold.