Don't think he has enough value to BOS to justify the expense. Timelord is better as starter. Horford still has value switching between the PF and C positions; not sure I want Horford exclusively as a PF, I prefer him as a combo. Without Horford exclusively at PF, Adams doesn't have enough minutes.
I'd rather spend the TPE elsewhere on a wing player. That position is a better fit and thus better able to justify expenditure.