Build-to-rent developers is corporates getting into the rental game isn’t it?

Yes. I believe it's actually the norm in some other countries, such as America. I'm ambivalent about it, to be honest. More big corporates getting involved could have upsides, like a greater degree of professionalism and potentially being more responsive to serious issues than bad individual landlords. Many individual landlords will blatantly break the law not out of malice, but just sheer incompetence. And because they're a relatively small target, the chances they face legal repercussions are minimal. A larger landlord with hundreds of tenants has a much larger legal risk if they do it on purpose (at least in theory—before regulatory capture sets in), and will have procedures in place to avoid it

But it could have very serious downsides, like never being as good as a good individual landlord who chooses to allow something they don't actually have to, and creating a more oligopolistic market that gives the landlords more power in the wider market than they currently do. It also means they have more political power to change the laws than they currently do, in theory (there's an argument for precisely the reverse: that policies that help landlords are an easy sell to the voting public when the landlords are mum-and-pop shops as policies that help people's "retirement nest eggs", whereas when it's a corporation it's harder to convince the public)

Ultimately, to me who owns the property matters much less than what the law says they can do with it. If it's impossible to evict a tenant who isn't causing damage without a really good reason (a legitimate need of serious repairs—which occurred for reasons that couldn't have been avoided by doing regular routine maintenance), the landlord or an immediate family member moving back in (with serious fines for not actually moving back in long-term after this reason is used), if the tenant is able to make minor reversible modifications like hanging up paintings or painting the walls, if they are required to be able to pay through reasonable convenient fee-less means, if they are protected from obscene rent hikes, and if retaliation against a tenant who tries to enforce their rights is penalised harshly, it doesn't matter much to me whether my landlord is Joe Blow or Apartments Incorporated.

to the uncompromising domination of a rental-corp

True, but for the reasons partly stated above this may not always make things worse. Plus, many if not most individual landlords go through a realtor anyway, who does most of the actual work. Does the rental-corp owning the building vs managing it on behalf of an individual actually make that difference? Maybe. Maybe not.

Reducing this support will likely deflate house prices a little, so the timing of changes like this would need to be considered carefully

I honestly reject the notion that policies that "deflate house prices a little" need to be "considered carefully". Deflating houseprices should be seen as a good in and of itself. That said, I think it should be done by way of reducing incentive to invest in housing, not reduce incentive for someone to own their own home. The end goal is making it more affordable for people to live. That means house prices and rent need to go down. For that, demand needs to be reduced without reducing the buying power of people who don't already own a home.

But regardless, voters aren't going to look at the nitty-gritty details. They'll see this headline and see "the Liberals want to make it harder to own a home". That can never be a vote winner. Nor can continued climate denial. Their base already votes for them on that account, but the vast majority of Australians accept the reality of climate change. The Liberals just need to keep climate change as far away from being a political issue as possible if they want to avoid losing potential votes.