This is a strange and interesting thread. Anyway,
A search on Indian trademark database shows it is a registered trademark. (Attached image). Trademarking requires lot of legal documents, so the company must have everything in place.
Plus the website says they were featured on NDTV and indoatoday (I'm not saying this is true, but it is easily verifiable and hence they would not put that on the website if it weren't).
As for question on 1L students, well it says tie up with 800 school, so it's not difficult to reach 1 L students. Nothing very suspicious there as well.
Also, I would say since the workshop is being conducted in the school, the school would have already done their homework on the credibility of the organisation, don't worry. If anything is wrong, the school can always be held accountable.
If anything, seems like a positive thing that someone is trying to teach our kids about this very interesting area of astronomy! Let them enjoy.