It did indeed say this, I saw it and can vouch for it.
It was new, it hasn't said this before. It is the only concrete statement stating the "for life" without caveat that has ever appeared.
It does, however, seem a little odd given that you appear to have been a big enough "cheese" to have negotiated a very special type of Club Rouge deal for your play, and suddenly find yourself kicked out whilst many others so far have not been.
Maybe you squeezed their balls a little TOO hard in the past, and they have now decided enough is enough.
It's also possible that this change is related to the expected increased costs of the new UK regime, where 15% of their profit on UK players will be going to the taxman, instead of about 2%. On top of this, there is the added cost of administering the regime so that they can correctly calculate the taxes due, as well as ensure compliance with the new regulations. In order to balance the books, these additional costs will have to be met by savings elsewhere. It is something that has deterred many casinos from staying in the UK.
My usual response to a casino that does this kind of thing to me is to call their bluff. I just stop depositing and see if they flinch by sending a "please come back" email and a revised offer. It's surprising how often this works

If it doesn't, then you know the casino isn't bluffing in an attempt to make you deposit more, they really meant it, in which case no amount of fuss is going to make them change their mind.