Both these arguments are true.
"Japan was ready to surrender" should be interpreted as "Japan wanted to surrender if the terms were acceptable".
To spell it out for you:
Japan was ready to surrender before atomic bombs, but held back because the allies terms were unacceptable, and Japan were hoping to get better terms, using USSR to mediate them.
Only when that hope was removed (by USSR declaring war on Japan) did Japan realise they had no other choice. And then they actually surrended.
The post I replied to very specifically says "Japan was ready to surrender" should be interpreted as:
"[Before the atomic bombs were dropped], the Imperial Japanese Armed forces were already signalling a willingness to end the war, with the one condition that the Japanese emperor ... would not be harmed."
I don't know why you're trying so hard to read things that are not there.
To spell it out for you: Japan was ready to surrender before atomic bombs, but held back because the allies terms were unacceptable, and Japan were hoping to get better terms, using USSR to mediate them. Only when that hope was removed (by USSR declaring war on Japan) did Japan realise they had no other choice. And then they actually surrended.