Sadly, Glenn never has an opportunity to witness his show of stamina. Poor Maggie has it trimmed off with seeing her boyfriend, and likely endures through a worse day than Glenn. After everything she survives, Glenn can comprehend why she shows the precise location of the remaining part of the crew.
Obviously, most of the crew is not indeed at the penitentiary now. As the Rick cavalry is coming to save the day, Glenn is right with his danger to Merle. I am still going to put all my bets on a Rick success, although they may be totally outnumbered.