Chip has been around for a few years and intends to be around and growing as a company in the future - it is clearly not just a scam or similar.
It would be very bad publicity if they were to advertise a bonus and then decide to not pay said bonus. Each person they did that to would withdraw their funds, they might also make a fuss on review sites and other forums. There seems to be no reason why Chip would choose to withhold bonus.
@Phrase2 said above that bank terms would say, effectively, “interest is paid at our sole discretion and is not guaranteed.” I checked a few banks’ terms and none said that, so I don’t really know why Chip would have this term but the bonus isn’t interest so maybe that has something to do with it.
I don’t know how this term would protect Chip from third party fraud, but if the app was being used for money laundering then I can see that they wouldn’t want to have to pay the money launderer a bonus that, without this term, they would presumably be obliged to pay.
I respect your decision to not use the product because of this term but, what is the worst that can happen? You don’t get paid the bonus and lose out on a maximum of £43 over 12 months (if my maths is correct – (£5000*0.0125)-19.5 ). As I say above, this would be a stupid tactic for a company that is trying to establish itself in the market etc.
I think MSE’s response to your concerns is fair enough. I have no idea whether they read the terms of every product they promote/feature but I don’t think they are in the habit of advertising offers that they don’t believe to be true. I note you say they have “advertised things before without telling the consumer” but I haven’t personally had any problems with them.
My previous post in the thread was querying the reason for the term. Whilst it would have been nice to have something “from the horse’s mouth,” the reason that Chip have apparently given to MSE when asked sounds sort of logical, and I still firmly believe that they are not going to actually use this term. Yes, they have the right to, but… see above.
Up to you, but I don’t think there is anything to lose (unless you are a money launderer, in which case avoid ).