This is a solid claim, however the available research does not support it. Caffeine is not all bad, it can be used to treat adhd symptoms as well as for attention performance & having neuroprotective effects. Your claim about calcium consumption is true, caffeine can stunt calcium absorbtion. What you failed to mention was caffeine can also cause iron absorption deficiency, weight loss, and effects sleep schedule. All of these factors have been shown to stunt growth in children. The claim that there is no evidence for caffeine affecting growth is simply false.
https://www.mdpi.com/1660-4601/17/7/2489
"Its use among children is controversial. Although it produces an increase in brain activity, it could hamper growth and development in young consumers."
"The results obtained showed that caffeine consumption hampers children’s growth and development. In contrast, it supports the activation of the central nervous system and brain energy management."
"On one hand, the literature has shown evidence of alterations in children’s growth and development, such as iron absorption deficiencies and weight loss. On the other hand, the physical, mental, attention-performance, and neuroprotective effects of caffeine have been demonstrated. "
"On the other hand, the negative effects include changes in the sleep cycle, which could indirectly alter the weight and growth of children, and greater sensitivity to the alkaloid at an emotional level (anxiety and depression)."