To me the terms and conditions are messy and should be changed. The player clearly fell foul though of rules that were reasonably clear but that does not change the following:
a) Harry Casino's defence on the issue included stating that the player had agreed to T&C's when signing up to the casino that they would be the final arbiter of any dispute - This is a totally BS clause that should not be in the T&C's, would not be enforcable in many legal jurisdictions (I am trained in private international law) and is not helpful to any amicable resolution.
b) Having a last updated clause to T&C's would be helpful - this should be promoted as good practice
c) If a bonus is offered but there has been a recent change to bonus terms then obviously casinos should point this out or give considerable latitude to the T&C's
d) Messy bonus terms are bad for business - people will either stay clear or gamble then complaint. They are not in the casinos interest and they could be easily changed so that they were more easily understood. Despite this though many bonus terms are just bad copy jobs from one casino to another by someone who has not read or understood the rules and as rules are modified they are done in a way that increasingly makes rules more complex and less coherent rather than in a sensible way trying to provide rules that are easy to read and understand.
e) Just because the WR goes down does not mean a bet "counts" for the WR within the rules - that is defined by the contract, not the coding. Players would have a much better time with bonuses if they were prevented from doing things that contrivened the bonus terms (large bets, prohibited games etc) but casinos either cannot or will not impliment these.
As for the player in question - getting your deposit back is probably the best you can hope for having signed up for a bonus and clearly violated the 25% bet requirement. Most casinos will regard big betting as against bonus T&C's so if you want to play in this way you really do need to read the T&C's closely before making deposits and either bet in ways that are clearly 100% within the T&C's or get clarification first before doing so. Otherwise this will not be the last casino you will end up in problems with around bonus issues whether it is specific clauses, ambiguity being interpreted against you or "spirit of bonus" problems.
This is one of the biggest problems, and one likely to make most of these terms void if it ever went to court. Given that the casino argues that this is a legal contract, it should be drawn up with the respect such a document warrants, not cobbled together from a bunch of cut & pastes from various other sites by someone who has English as a second language.
When courts hear such cases, a subtle grammatical difference can completely change the meaning of a contract. Casinos should treat their terms with the respect they deserve, having them drawn up by someone with English as their first language, or who are very fluent in it as a second. This person also needs to be legally trained to a level that enables them to convert what the casino intends into a clear and unambiguous set of contract terms that would stand up to the scrutiny of a civil court.
Whilst operators' claims that such things can't be enforced through the software, this is a "can't be arsed to" rather than "not technically possible". Cynics argue that watertight enforcement via the software would deprive casinos of the abilty to void winnings when they feel the player has got one over on them, but can't prove it, sometimes expressed as "spirit of the bonus", or "played in a professional sense".
Although the 25% rule is vaguely worded, if the offending bets were more than 25% of the bonus credited, it would be a watertight case for the casino, as this is the most liberal interpretation possible.
Casinos should also avoid the vague use of "may" and "reserve the right" when they mean "will". They should also call a prohibited game a "prohibited game", not mince their words by saying "does not contribute to WR" or "weighed at 0%".
When changes are made, the whole set of terms should be reexamined by the legal team to ensure that the changes do not introduce conflicts with existing terms, and that the wording achieves what is intended. The date from which the new terms apply should also be clearly stated, which can be done through having a "last changed" datestamp at the beginning.