I think it's perfectly understandable when people are at threads like this!
There have been a gazillion discussions explaining, often at length and with great patience, the needs of babies...which are individual, for sure, but which hardly ever equate to starting solids at age 4 mths.
There is no evidence that babies who are big, or who feed often (and 2 x a night and every 2.5 hours in the day is not all that often, anyway!) or who make 'chewing motions' need anything other than milk at this time.
However, it's also true that prob most babies who start solids as early as this show no ill effects, so if parents are determined to give them, then prob the best advice is to give the baby something pretty bland and harmless to hold (like a rice cake, or a piece of pear) and see what happens!
There is really no nutritional benefit in spooning in cereal, no matter how cute the baby looks [hmmm]...that's not my opinion, it's the facts