Either greed or TK actually believed the merger would bring each company's technology together to leverage across all product lines. Remember the technology story was TK's primary explanation as the reason for the "merger".
Let's examine the technology reason. If this is true, TK and the legacy Raytheon leadership completely misunderstood the UT business model. UT is a decentralized company which buys profitable companies and allows these companies essentially run independent of corporate control. UT buys companies solely because they are profitable. There is no UT corporate strategy to share ("leverage") technology across companies. UT simply has no mechanism for this process to occur.
There is evidence of legacy Raytheon buying companies for technology (Solypis, BBN Technologies, Blue Canyon, etc.) so perhaps this mindset drove the UT merger. Note many recent purchases resulted in failure: Forcepoint (note acquired for $2.5B, sold for $1.5B), JPS Communications closed and sold in 2016. So, perhaps TK and his leaders actually believed the UTC merger would bring the best of each company's technology to the forefront for enterprise use.
Greed? One only has to examine the merger related SEC filings to realize the enormous amount of compensation paid to displaced legacy Raytheon leaders and to those retained in the new company. As an example, Randa Newsome, legacy HR VP profited over $13M in the award and sale of company stock related to the merger.