The ITV bulletin ended up being almost an hour earlier rather than 30 minutes as you claim. The bigger issue with the timings of the news is arguably the length of time that it left between the 2 bulletins which could well have led to not insignificant overtime payments and other additional costs. The fact is though that we fail year after year in eurovision and don't even seem to be making much effort so if anything it should be eurovision that is moved to BBC2 to allow BBC1 to run with a relatively normal schedule.
The ITV bulletin was on at 11.30, compared to 12.10 for the Beeb, I wouldn't argue that was a great deal different. If there was a genuine need for an earlier bulletin then ITV would presumably have spotted the gap in the market and filled it. Pretty sure the additional costs required were totally trivial in the grand scheme of things, Saturday night is an inconvenient slot for many people regardless of whether it's half ten or half twelve.
As for the point about the requirement for "a relatively normal schedule", I will say again, every other week of the year we get complaints that the schedules are staid and boring and should be ripped up, and the second they deviate from them in any way, apparently they need to have a normal schedule because people are devastated that the regular programmes aren't on. People can cope the one day in 365 when the BBC1 schedule goes a bit funny.