Do you have an references for expedited removal being applied to LPRs? That link you included has this:
"Lawful Permanent Residents (green card holders or LPRs): You only have to answer questions establishing your identity and permanent residency (in addition to customs-related questions). Refusal to answer other questions will likely cause delay, but officials may not deny you entry into the U.S. for failure to answer other questions. LPR status may be revoked only by an immigration judge. Do not give up your green card voluntarily!"
Which strongly implies that CBP can't use expedited removal or consider you inadmissable when you apply for entry. You could certainly be detained until you are seen by a judge though (probably not much better) and I've heard of people being pressured by CBP to fill out a I407 (surrendering your LPR status) and then being removed.
"Lawful Permanent Residents (green card holders or LPRs): You only have to answer questions establishing your identity and permanent residency (in addition to customs-related questions). Refusal to answer other questions will likely cause delay, but officials may not deny you entry into the U.S. for failure to answer other questions. LPR status may be revoked only by an immigration judge. Do not give up your green card voluntarily!"
Which strongly implies that CBP can't use expedited removal or consider you inadmissable when you apply for entry. You could certainly be detained until you are seen by a judge though (probably not much better) and I've heard of people being pressured by CBP to fill out a I407 (surrendering your LPR status) and then being removed.