While I rarely share my opinion on this sort of thing, as I know one of the people involved I thought I'd share my thoughts. So, I know Tom (ProSyndicate) not super super well, but we worked together on YouTube (Minecraft content) for a few years and I personally have appeared in videos with him and such.
If he legitimately called out to go to this CSGO Lottery Site and said that he found it (rather than founded/owns it)...etc then that's clearly directly lying to his audience and misleading them. I would actually suggest that saying he owns it and is apart of it may actually get MORE of his audience to use it - people love that sort of shit especially big YouTuber endorsed sites/games. I wonder if there's something in the YouTube advertising/content creator terms of service about promoting gambling without age restrictions on your videos and maybe that's why they don't want to promote the site as something they own?
Anyway, I don't know this TmarTn guy but Tom has always been nice and quite forthcoming online and in person so I don't think he or those he'd associate themselves with would be inherently malicious but that's just my assumption - maybe there's much more to this than meets the eye.
Edit: Just a quick follow up as I'm reading some of the articles. If they truly did say that they 'found' this website and had no prior knowledge then it's a total dick move - however, I've seen people show off websites and take part in games they've made without even mentioning they were involved in there creations before - this, however, does not look like their approach when talking about this Lotto in their videos.
Edit 2: After reading more and more, clearly this was a direct act to promote and gain income from gambling on their own site. Many of those involved acting as if they had never heard or seen the website initially. This is a poor use the of trust of the subscribers, fans, viewers...etc and also a directly legal violation. Not cool at all.