Defender Purches suffered concussion and a split lip following an aerial clash with County striker Lee Hughes during Cherries' 2-0 win at Meadow Lane on Saturday.
Purches collapsed in a heap and required lengthy treatment after appearing to be caught by a flailing elbow from Hughes early in the first half.
The injury forced off Purches at half-time, with Cherries boss Lee Bradbury confirming the decision to substitute him had been taken following consultation with the County club doctor.
New County boss Allen, speaking to reporters during his post-match interview, said he had been unable to comment on the flashpoint as he had not seen it.
However, Echo reporter Neil Perrett yesterday followed up by sending a personal tweet to Allen, asking why he had failed to see the incident when it had taken place in front of his technical area.
And within minutes, Allen had posted a reply claiming he had been watching while a throw-in was taken and had not witnessed the aerial challenge. He went on to describe Purches as a good lad and not a faker.
Cherries boss Bradbury, asked by the Echo for his view of the incident, said: He did lead with his elbow. Whether it was intentional or not, only he knows.
Purches politely declined to comment on the incident.
Hughes, who was appointed skipper by Allen last week, was later booked by referee Andy Haines after appearing to lead with his arm in a challenge with Cherries skipper Jason Pearce.
The 33-year-old former West Brom striker was also involved in a spat with Adam Smith following the final whistle.
Hughes, who had earlier exchanged words with the defender, had to be restrained, with both Allen and Steve Fletcher intervening. Smith, meanwhile, was led away by members of the Cherries staff.