Regret, incommensurability and utilitarianism

I'm fairly sure there's a large established literature on regret that I'm unfamiliar with, so apologies if I'm rehashing old arguments.

In Moral Reasons (p121), Jonathan Dancy alludes to (but doesn't endorse) the following argument against utilitarianism:

1) Utilitarianism is not value-pluralist.

2) A theory must be value-pluralist in order to make regret rational.

Conclusion:
3) Utilitarianism cannot make sense of regret.

One response to this is to simply accept (3) and remain utilitarianism nonetheless. If regret and utilitarianism are incompatible, so much for regret.

But it seems to me that premise (1) is unsound anyway.

Utilitarians ought not to think that there is some individual giant bowl of utility that we may add to or take away from. The value of utility is not homogenous.

Instead, they ought to maintain that each person's utility has unique value. Utility maximisation is a result of this fact, not the fundamental aim. Utilitarians therefore seem to be able to make sense of regret in terms of the value that we could not realise for those who fail to benefit from any action. The value that we could've gained from an alternative action is therefore not value of the same kind that our current action did in fact produce. The alternative action produced alternative value - value for someone else.