Are Triceratops and Eotriceratops similar enough to be considered as the same genus?
Taxonomists have wide leeway over assigning higher taxa. The publication process in which Eotriceratops was described as a new genus made it a new genus. However, given a different set of reviewers, they may have rejected the new generic description, and suggested that the author put it into Triceratops. The process is somewhat arbitrary, and there are some random elements to higher taxon assignment. But it is the system we use. If somebody were to write a paper to synonomize Eotriceratops with Triceratops, and that paper were accepted, then Eotriceratops would cease to be a valid name. Its all about publication precedence. Gregory  Paul may have good reason for his suggestion, but it must be published before a change is made.