If anything, even a negotiated "safe word" likely provides no legal protection from a rape charge. The default is "no means no", so it may technically hold even in BDSM, and it all rests on whether one party decides to charge rape.
I know of no relevant cases, so its largely a hypothetical to evaluate logical implications of the law, even if the absence of any such accusations means it is a "problem" for BDSMers that doesn't really need a solution.
That would be a terrible law as it would define perfectly consensual sex as "rape".
Now, things probably vary by state but in the Columbia case I mentioned the judge (using "rape shield law") improperly excluded emails between the false accuser and her victim detailing their plants to engage in BDSM and he was convicted. Luckily an appeals court found in his favor and he was freed, but not before spending almost two years in prison and getting attacked there. However, that shows that at least in New York consensual BDSM would be a valid defense against bogus rape claims (unless the judge improperly excludes exculpatory evidence).