I can't speak for everyone else, but I wrote about this exact thing recently (Rainbow Washing & False support of Pride by Corporations/Politicians for financial gain etc)
I absolutely scrutinise all the other forms of corporate ass-holery too. The only difference, that I feel anyhow, is it's considerably easier to point out the stark contrast between certain corporate actions during pride month, and their actions outside of pride month. It's a unique situation where we haven't been experiencing this for so long that it's simply business as usual.
For me, it's not a question of hating pride and using this as a means to push through hateful rhetoric – It's definitely just a case of tackling one thing at a time. Though I absolutely will concede that you're more than likely correct in your assumption that social conservatives will attempt to hinder the pride movement by wrapping up their bullshit rhetoric and policy in social justice.
Is it maybe more about 'work for us'? Like celebrating Christmas isn't usually an attempt to recruit Christians, but displaying pride colors signals that you want to be seen as a safe place for people to work?
What do they do after Pride Month that's so bad? Yeh it's just a corporate cash grab, and it's funny how the Middle Eastern branches of these companies don't change to a rainbow profile pic, but what do they do that's so wrong?