There are two reasons for these doubts. Firstly, none of these four leaders have criticised the TDP. Secondly, Chandrababu Naidu said nothing against these four MPs. Normally, turncoats will be more than willing to attack the parties that they just left to curry favour with the new dispensation. This is not being seen in this case.
In fact Sujana Chowdary termed Chandrababu his political guru and said that the TDP would come back to power again. Ditto with CM Ramesh. They have said pretty much nothing about why they were joining the BJP. Also, despite early warnings that these four MPs could join the TDP, Chandrababu continued with his foreign vacation and said nothing about their actions. Interestingly, he has asked his partymen not to say a thing against the four MPs. He directed them to criticise the BJP if they wanted.
So, the big question is are these TDP coverts in the BJP? Will they come back to the TDP when the tidings are favourable? Or will they slowly merge into the saffron party? For this, we may have to wait till 2024.