I think you've hit the nail on the head. Each person will hear that statement differently, depending on context and depending on the unconscious agendas at work in both parties, and even on the current moods people are in at the time of the conversation.

I think what disturbs me a bit is I find it infantilizing rather than empowering. I think if someone has a dominant core yearning for a mother it's going to be really easy to read lots into a simple statement like that and hear it as "I really want to take care of you, and do this thing primary caregivers do for young children". I think it is mothering of sorts. Maybe it's ok for a T to mother clients in this way, I don't honestly know - I guess many of us need need reparenting (recalibrating?) in different ways, some more overt than others. However, this T said things like "I don't know if this is appropriate" which rings alarm bells - that sounds like she's winging it.