I'm not familiar with the post you reference, so I'll just give my answer straight:
I don't have a hard line about crying. My goal as a parent is to help my child to feel safe, secure, able to depend on me, and to help him learn resilience as he grows. So yes, when he was an infant and toddler, I was very responsive to crying. As he got older, I could sometimes give empathy ("I know, you really like the park, let's say goodbye to the swings and slide, they will be here next time.") and sometimes, it was more "well, I guess he's going to have to scream in the stroller as we are walking away, because he's mad to be there and he won't walk" and just ignored it.
I think kids are little people who need to express themselves, and hopefully, as their parents, we can help them do it as appropriately as possible. Sometimes, it's going to be awful, esp. when they are sincerely sad that they have to leave off something fun or can't have a desired item. There's a difference between sad crying and a self-indulgent tantrum. Their developing brains haven't really progressed beyond "fight or flight" and "loss=pain" responses, so the anger of a two year old is processed in the part of the brain which processes pain; the anger of a seven year old (as my son is now) is more easily listened to (they have better expressive skills), can be addressed with problem-solving strategies and is less likely to have a profound or long-term impact because the child is more mature.
All that to say, much of how I deal with tears is related to what I know of child/brain development and the individual child's level of development. Keeping in mind, too, any significant transitions which may be happening in the child's life. I was a nanny and preschool teacher for years and so I worked with children going through various transitions; they each needed to be individually considered. Transitions often throw children off and threaten their sense of security and predictability-- that child needs more empathy and guidance than they go separation.
My motto is to 'never, ever try to reason with a tantrum'. I just give him a place to have the tantrum safely and walk away. Tantrums mean that a child's emotions have become out of control, even for them-- not a time for a long discussion.
I will also say that while *I* might think there's 'no good reason' in the moment, I do try to consider not just the one incident which started the crying, but the whole of the day. If it's been one disappointment after another, it CAN be a little, insignificant-to-us-adults thing which will set kids off. Then, I'll offer some empathy and see if I can't throw them a bone by helping them consider what they have to look forward to. Because we all have bad days--- kids just process it differently than adults. Adults may not cry in the face of disappointment, but I have seen parents pick at their kids for every little thing out of misplaced frustration or anger. We are just as much of a problem sometimes as the kids can be, just in different ways.
I find it's better for me to parent with an open heart and being aware, trying to connect to what the 'root' of the problem is than for me to have any hard and fast rules. Self-indulgent behavior -- my son has the option of cooling it or taking it to his room, and I also try to make sure that I'm clued in enough to know what's troubling him.
ETA: I see your SWH. I guess what I'm wondering is if the kid needed to just hang out and watch for the first couple of sessions. Some kids are observers. Don't know....I know my son took some time to warm up to jumping into his judo class at the beginnings, now he readily joins, he's seven. Each kid has their own personality and their own anxieties. If he'd cried, I would have removed him to outside instead of telling him to stop crying. Dunno...