"France has been great. They've all been great. The UK has been much different from others." (I guess he just forgot about Spain being dicks lol.)
This is not surprising, Starmer is a weak man who is wedded to notions of diplomacy and international rules-based faggotry. I will be a little fair to him; he is in a really shitty position domestically. Labour is extremely unpopular and his own MPs are clutching daggers to snake him at any moment. Given how unpopular foreign wars are right now, it would be politically stupid of him to commit British forces to a regime change in Iran, especially when the present military consensus in the UK is that Russia is the priority threat.
The problem isn't actually much to do with how Starmer has been acting in the context of Iran but in the wider political picture, primarily with Diego Garcia.
Diego Garcia is imperative for US interests because it serves as a base in the Indian Ocean in a vital position that keeps it within the reach of Africa, the Middle East, and even India. It is there that the B-2 operations were launched in the 12 days war. It is also in a very isolated location which makes it great for not having observers and it means a lot of information can be kept classified.
But, Britain is wanting to give up the islands and hand them back to Mauritius on the basis of it being previously apart of the same colonial administration body (which is dumb, colonial administration bodies were constantly changing. Case in point, Mauritius not claiming the Seychelles which were apart of British Mauritius in the early 1900s). This is a Uniparty decision btw, supported by both Labour and Tories (the Tories were the ones who started pushing it).
The problem? Mauritius is aligned with China and whilst it is true that the UK will formerly reserve the right to VETO bases being developed in the Chagos Islands. India has already expressed interest and negotiated to build a RADAR station in the vicinity. It is likely that in the future Mauritius would declare that "the clauses on UK VETO power go against our territorial integrity" and thus just go ahead renting islands to others.
In theory, the UK actually has one of the best Blue-Water capabilities when it comes to project power. Better than China in pretty much all regards (China does not have the logistics for this, and is constrained to the 1st island chain which is their current focus). Britain and France basically tie for 3rd place when it comes to power projection - though Britain does have the better carrier capability, in theory as France has only 1 CV which means they can't have constant fixed wing aviation.
And with Trump's perspective of wanting "everyone to pitch in"? Well, he's starting to lose his fuse. A British carrier would have been critical in augmenting anti-Tehran power in the region. Where, a Queen Elizabeth Class is capable of having 72 Aircraft in war time. - Which despite Britain not having enough F-35s for that, they would have been able to deploy American fighters from them which have happened in the past (the integration tests with F-35s took place before Britain received their first deliveries).