Sounds pretty circumstantial. Adobe for example has had many security vulnerabilities in flash over the years. I doubt that they were intentional back doors.
An average antivirus software has everything necessary already. Personal licenses as a way to identify the specific machine or person, automatic streaming software updates as a way to deliver the payload and almost unrestricted privileges on the target system enough to infiltrate and stay concealed.
As an example, there's still room for argument about the Dual_EC_DRBG algorithm, and RSA making that the default PRNG for some or all of their products. RSA denies taking money for it. Nobody can make an airtight case for the NSA deliberately weakening it. Yet we still all kind of view Dual_EC_DRBG with suspicion.
Not that RSA hasn't done so in the past, but it was public when encryption software could not be exported RSA cam to an agreement with the US government to export it's 64bit encryption, it would use a 40bit private key and append the message with an additional 24bits which are transmitted in clear text and complete the private key to it's 64bit size.
This was a government mandated "work reducer" so the NSA if need be could decrypt the message as they had the ability to break 40bit encryption and the rest of the 24 bit of the 64bit encryption key was known for each message. This wasn't hidden, this was even released in a conference with great pride that RSA could now export it's mail encryption suit to Europe. Germany made a fuss about this 5 years after the fact, but everyone pointed and said well they announced it in a conference.
It's strange to think that corporate employees would be that much harder to corrupt, especially for their own country.
1: https://en.wikipedia.org/wiki/Robert_Hanssen 2: https://en.wikipedia.org/wiki/George_Trofimoff
I know of employees busted for internal schemes they cooked up (it was pretty cool working with BigCorp to setup an international sting to get them). It simply cannot be that hard to find people that need or want money and get them to compromise things for relatively small amounts of money.
Human assets is a different story, 1.4 and even 250K while not being a large sum is quite a large amount of money. Those assets are usually developed by other means, in most cases the money is largely irrelevant even if the asset refuses to take money tradecraft mandates that they'll be forced to take it it just to leave a money trail that they could then be threatened with if they no longer with to comply. Additionally being paid also makes the asset more invested in their duty because it creates a link like with a would be employer, and allows them to quantify their assignment with a positive reinforcement no matter how big or small it is. So money which is paid to long term assets isn't really a bribe, an initial sum might be used to turn the asset in the first place but it also usually require them to be in a position to need it e.g. gambling debts, medical bills etc. Generally assets that can be bribed will not be farmed in such manner as the cases you've mentioned, people that can be easily bribed cannot be trusted which isn't a trait you want in an asset.
Even without that - it's free money for a benign reason, while doing the security services a favour. "Hey we've got this new crypto thing that's amazing but people don't believe us. Add it to your product, and we'll give you token compensation. Also we'll also make a note of what great guys you are."