I suppose you could be worried about it if you want to, but the OP at xda is in Dubai. SIT Distribution is a real company (simple google search) and according to salman22 they are "the official distributors for HTC in Dubai, UAE." Another poster from Dubai had also heard of the promotion.
I'd bet the IMEI is to ensure that only residents of Dubai and whatever carrier(s) are running this promotion are able to download the games. Though, it seems they may need to work on their website design since the link you get after putting in your IMEI apparently works for anyone.
Edit - if you're still worried, you can read post MykeChester's post
here. He has lots of posts on xda and is in Dubai. Posting over 800 posts over the course of a year and a half seems a little far fetched for someone trying to make your phone send text messages on its own...