Is there a difference of opinion regarding the ruling on one who hears blasphemy, and does "without condemnation" mean not condemning verbally, given that I condemn it in my heart?

The listener does not share the speaker's disbelief unless he acknowledges or approves of it. The verse "Indeed, you would then be like them" means resemblance in disobeying Allah's command and committing a sin, and not a complete resemblance in disbelief. So, whoever is not pleased does not become a disbeliever, but rather commits a sin for not denouncing it. The resemblance in the verse is meant for emphasis and warning, not that a believer becomes a hypocrite merely by sitting with them. And whoever is unable to denounce with his tongue, let him denounce with his heart, and he is obligated to stop sitting with them.