No they're not rogued.
Many reputable MG casinos (including quite a few CM accredited casinos) have these same offers - they all say just "Keep your winnings!" on the promo banners, but ALL of them have max amount you can actually claim.
I find it bloody annoying that otherwise good casinos use this "deceptive marketing" to try to attract new players, but the bottom line is the max win is clearly stated in the T&C's.
I hope this link is OK, but if you go to my
page and scroll down the the Microgaming section at the bottom you can see I have 20 such offers listed; for each I have checked ALL the T&Cs and stated what the max win is from each in the left-hand column.
Some of these offers are actually very good... and some are crap. I provide the information so people can make up their own minds.
KK
PS: If you're in Houston TEXAS you can't claim any of these bonuses anyway!